Connection of the foregoing with the sequel

I meditated on all your operations: I meditated upon the works of your hands.

Psalm 143(142):5

It is impossible to know a thing perfectly unless we know its operation, since from the mode and species of its operation we gauge the measure and quality of its power, and the power of a thing shows forth its nature (because a thing has naturally an aptitude for work according as it actually has such and such a nature).

Now the operation of a thing is twofold, as the Philosopher teaches in Metaphysics 9:¹ one that abides in the very worker and is a perfection of the worker himself, such as to sense, to understand, and to will; and another that passes into an outward thing, and is a perfection of the thing made that results from it, such as to heat, to cut, and to build.

Now both of the aforesaid operations are competent to God: the former, in that he understands, wills, rejoices, and loves; the latter, in that he brings forth things into being, preserves them, and rules them. Since, however, the former operation is a perfection of the operator, while the latter is a perfection of the thing made, and since the agent is naturally prior to the thing made and is its cause, it follows that the first of the aforesaid operations is the reason of the second, and naturally precedes it, as a cause precedes its effect. This is, in fact, clearly seen in human affairs: for the thought and will of the craftsman is the origin and reason of the work of building.

Accordingly, the first of the aforesaid operations, as a simple perfection of the operator, claims for itself the name of operation, or again of action: while the second, as being a perfection of the thing made, takes the name of work.¹ Hence things which a craftsman brings into being by an action of this kind are said to be his handiwork.

Of the former operation of God we have already spoken in the foregoing book, where we treated of the divine knowledge and will.¹ Therefore, in order to complete our treatise of the divine truth, it remains for us to treat of the latter operation, namely, that whereby things are made and governed by God.

We may gather this order from the words quoted above (Ps 143[142]2:5). For first he speaks of meditation on the first kind of operation, when he says: I meditated on all your operations, so that we refer operation to the divine intelligence and will. Then he refers to meditation on God’s works when he says, and I meditated on the works¹ of your hands, so that by the works of his hands we understand heaven and earth, and all that is brought into being by God, as the handiwork produced by a craftsman.

That the consideration of creatures is useful for building up our faith

This meditation on the divine works is indeed necessary in order to build up man’s faith in God.

First, because through meditating on his works we are able somewhat to admire and consider the divine wisdom. For things made by art are indications of the art itself, since they are made in likeness to the art. Now God brought things into being by his wisdom: for which reason it is said in the Psalm: in wisdom have you made them all (Ps 104[103]:24). Hence we are able to gather the wisdom of God from the consideration of his works, since by a kind of communication of his likeness it is spread abroad in the things he has made. For it is said: he poured her out, namely wisdom, upon all his works (Sir 1:10); therefore, the Psalmist, after saying: your knowledge is too wonderful for me; it is high, I cannot attain it (Ps 139[138]:6), and after referring to the aid of the divine enlightening, when he says: let only darkness cover me, and the light about me be night (Ps 139[138]:11), confesses himself to have been helped to know the divine wisdom by the consideration of the divine works, saying: wonderful are thy works! My soul knows right well (Ps 139[138]:14).

Second, this consideration leads us to admire the sublime power of God, and consequently begets in men’s hearts a reverence for God. For we must conclude that the power of the maker transcends the things made. Therefore it is said: if they, the philosophers, were amazed at their power and working, namely of the heavens, stars, and elements of the world, let them perceive from them how much more powerful is he who formed them (Wis 13:4). Also, it is written: ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made (Rom 1:20). And this admiration makes us fear and reverence God. Hence it is said: your name is great in might. Who would not fear you, O King of the nations? (Jer 10:6–7).

Third, this consideration inflames the souls of men to the love of the divine goodness. For whatever goodness and perfection is generally apportioned among various creatures is all united together in him universally, as in the source of all goodness, as we proved in the first book.¹ Therefore, if the goodness, beauty, and sweetness of creatures are so alluring to the minds of men, the fountainhead of the goodness of God himself, in comparison with the rivulets of goodness which we find in creatures, will draw the kindled souls of men wholly to itself. Hence it is said in the Psalm, you, O Lord, hast made me glad in your works; at the operations of your hands I sing for joy (Ps 92:4[91:5]); and elsewhere it is said of the children of men: they feast on the abundance of your house, that is of all creatures, and you give them drink from the river of your delights. For with you is the fountain of life (Ps 35:9–10). Again, it is said against certain men: they were unable from the good things that are seen, namely creatures that are good by participation, to know him who exists (Wis 13:1), namely, the true good; no, more: goodness itself, as we have shown in the first book.²

Fourth, this consideration bestows on man a certain likeness to the divine perfection. For it was shown in the first book¹ that God, by knowing himself, beholds all other things in himself. Since, then, the Christian faith teaches man chiefly about God, and makes him to know creatures by the light of divine revelation, there results in man a certain likeness to the divine wisdom. Hence it is said: we all, with unveiled face, beholding the glory of the Lord, are being changed into his likeness (2 Cor 3:18).

Accordingly it is evident that the consideration of creatures helps to build up the Christian faith. Therefore it is said: I will now call to mind the works of the Lord, and will declare what I have seen. By the words of the Lord his works are done (Sir 42:15).

That the knowledge of the nature of creatures avails for refuting errors against God

The consideration of creatures is likewise necessary not only for the building up of faith, but also for the destruction of errors. For errors about creatures sometimes lead one astray from the truth of faith, insofar as they disagree with true knowledge of God. This happens in several ways.

First, because through ignorance of the nature of creatures men are sometimes so far misled as to deem that which can but derive its being from something else to be the first cause and God, for they think that nothing exists besides visible creatures. Such were those who thought that any kind of body was God, of whom it is said: they supposed that either fire or wind or swift air, or the circle of the stars, or turbulent water, or the sun and moon were the gods that rule the world (Wis 13:2).

Second, because they ascribe to certain creatures that which belongs to God alone. This also results from error about creatures: for one does not ascribe to a thing that which is incompatible with its nature unless one is ignorant of its nature (for instance, if we were to ascribe three feet to a man). Now that which belongs to God alone is incompatible with the nature of a creature, even as that which belongs to man alone is incompatible with another thing’s nature. Hence the foregoing error arises from ignorance of the creature’s nature. Against this error it is said: men . . . bestowed on objects of stone or wood the name that ought not to be shared (Wis 14:21). Into this error fell those who ascribe the creation of things, or the knowledge of the future, or the working of miracles to causes other than God.

Third, because, through ignorance of the creature’s nature, something is withdrawn from the divine power in its working on creatures. This is evidenced in those who ascribe to things a twofold principle, and in those who aver that things proceed from God not by the divine will, but by natural necessity, and in those who withdraw either all or some things from divine providence, or who deny that it can work outside the ordinary course of things. For all these are derogatory to the divine power. Against these it is said: who looked upon the Almighty as if he could do nothing (Job 22:17), and: you show your strength when men doubt the completeness of your power (Wis 12:17).

Fourth, man, who is led by faith to God as his last end, through ignoring the natures of things—and consequently the order of his place in the universe—thinks himself to be beneath certain creatures above whom he is placed, as evidenced in those who subject man’s will to the stars. Against these it is said: be not be dismayed at the signs of the heavens because the nations are dismayed at them (Jer 10:2). Also in those who deem the angels to be the creators of souls, and human souls to be mortal; and in those who hold any like opinions derogatory to the dignity of man.

Accordingly, it is clear that the opinion is false of those who asserted that it does not matter to the truth of faith what opinions one holds about creatures, so long as one has right opinion about God, as Augustine relates in his book On the Soul and Its Origin,On the Soul and Its Origin 4.4. since error concerning creatures by subjecting the human mind to causes other than God amounts to a false opinion about God, and misleads the minds of men from God, to whom faith strives to lead them.

Therefore, Scripture threatens punishment to those who err about creatures like unbelievers, in the words of the Psalm: because they do not regard the works of the Lord, or the operations of his hands, he will break them down and build them up no more (Ps 28[27]:5); and: thus they reasoned, but they were led astray (Wis 2:21), and further on: they did not . . . discern the prize for blameless souls (Wis 2:22).

That the philosopher and the theologian treat of creatures in different ways

Now it is evident from what has been said that the teaching of the Christian faith treats of creatures insofar as they reflect a certain likeness of God, and insofar as error concerning them leads to error about God. And so they are viewed from a different point by the aforesaid teaching and by human philosophy. For human philosophy considers them as such; therefore, we find that the different parts of philosophy correspond to the different genera of things. But the Christian faith does not consider them as such—for instance, it considers fire not as such, but as representing the sublimity of God, and as being directed to him in any way whatever. For as it is stated: full of the glory of the Lord is his work. Hath not the Lord made the saints to declare all his wonderful works? (Sir 42:16–17).

Hence also the philosopher and the believer consider different matters about creatures. For the philosopher considers such things as belong to them by their own nature (for instance, that fire tends upwards). But the believer only considers about creatures such things as belong to them in respect of their relation to God (for instance, that they are created by God, are subject to God, and so forth).

Thus it does not argue imperfection in the teaching of faith if it overlooks many properties of things, such as the shape of the heavens, and the quality of its movement. For neither does the physicist consider the same characters of a line as the geometrician, but only such as are accidental to it, as the term of a natural body.

Any matters, however, that the philosopher and the believer consider in common about creatures are delivered through different principles in each. For the philosopher takes his argument from the proper causes of things, whereas the believer has recourse to the first cause (for instance, because it has been thus delivered by God, or because it conduces to God’s glory, or because God’s power is infinite).

Hence (the teaching of faith) should be called the greatest wisdom, since it considers the highest cause, according to the saying of Deuteronomy 4:6: this is your wisdom and your understanding in the sight of the peoples.

Therefore, human philosophy is a handmaid to her as mistress. For this reason sometimes divine wisdom argues from the principles of human philosophy, since also among philosophers the first philosophy makes use of the teachings of all sciences in order to establish its purpose.

Hence again both teachings do not follow the same order. For in the teaching of philosophy, which considers creatures in themselves and leads us from them to the knowledge of God, the first consideration is about creatures, and the last of God. In contrast, in the teaching of faith, which considers creatures only in their relation to God, the consideration about God takes the first place, and that about creatures the last. And thus it is more perfect as being more like God’s knowledge, for he beholds other things by knowing himself.

Therefore, according to this order, after what has been said in the first book about God in himself, it remains for us to treat of the things which proceed from him.

Order of the things to be said

We shall treat of these things in the following order. First, we shall discourse of the bringing forth of things into being;¹ second, of their distinction;² third, of the nature of these same things brought forth and distinct from one another, so far as it concerns the truth of faith.³

God’s power

That it becomes God to be the source of being to other things

Taking, then, as granted the things that were proved in the foregoing book, let us now proceed to prove that it becomes God to be the source and cause of being to other things.

For it was shown above¹ by the proof of Aristotle that there is a first efficient cause which we call God. Now an efficient cause brings its effects into being. Therefore, God is the cause of being to other things.

Again. It was shown in the first book,¹ by the argument of the same author, that there is a first immovable mover, which we call God. Now the first mover in any order of movements is the cause of all the movements in that order. Since, then, many things are brought into being by the movements of the heaven, and since God has been proved to be the first mover in the order of those movements, it follows that God is the cause of being to many things.

Moreover. That which belongs to a thing by its nature must be in that thing universally, as for man to be rational, and for fire to tend upwards. Now it belongs to a being in act that it should enact an effect, for every agent acts according as it is in act.¹ Therefore, it is natural to every being in act to enact something existing in act. Now God is being in act, as we proved in the first book.² Therefore, it is competent to him to produce something in act, to which he is the cause of being.

Further. It is a sign of perfection in things of the lower world that they are able to produce their like, as stated by the Philosopher in Meteorology.¹ Now God is supremely perfect, as was proved in the first book.² Therefore, it is competent to him to produce something in act like himself, so that he is the cause of its being.

Again. It was shown in the first book¹ that God wills to communicate his being to other things by way of likeness. Now it belongs to the will’s perfection to be the principle of action and movement, as stated in On the Soul 3.² Since, then, God’s will is perfect,³ it does not lack the power of communicating his being to a thing by way of likeness. And thus he will be the cause of its being.

Further. The more perfect the principle of a thing’s action is, to so many more and further distant things can it extend its action: thus fire, if weak, heats only that which is close, but if it is strong it heats even distant things. Now pure act, which is God,¹ is more perfect than act mingled with potency, as it is with us. But act is the principle of action. Since, then, by the act which is in us we are able to proceed not only to actions that abide in us, such as intelligence and volition, but also to actions that pass on to outward things, and through which certain things are made by us; much more can God, because he is in act, not only understand and will, but also produce an effect. And thus he can be the cause of being to other things.

Hence it is said: who does great things and unsearchable, marvelous things without number (Job 5:9).

That in God there is active power

It follows from this that God is powerful, and that active power is fittingly ascribed to him.

For active power is the principle of acting on another as such.¹ Now it becomes God to be the principle of being to other things. Therefore, it becomes him to be powerful.

Moreover. Just as passive potency is consequent upon being in potency, so active potency is consequent upon being in act, for a thing is active because it is in act, and passive because it is in potency.¹ Now it becomes God to be in act.² Therefore, active power is becoming to him.

Again. The divine perfection includes the perfection of all things, as was proved in the first book.¹ Now active power belongs to the perfection of a thing, since a thing is found to be the more perfect in proportion as it is more powerful. Therefore, God cannot be devoid of active power.

Hence it is said in the Psalm: you are powerful, O Lord (Ps 89:8[88:9]), and elsewhere: your power and your righteousness, O God, reach the high heavens; you who have done great things (Ps 70:18–19).

That God’s power is his substance

We may also conclude from this that the divine power is God’s very substance.

For active power becomes a thing according as this is in act.¹ Now God is act itself; nor is he being in act by some act that is not himself, since in him there is no potency, as we have proved in the first book.² Therefore, he is his own power.

Again. Whatever is powerful and is not its own power is powerful by participating in another’s power. But nothing can be ascribed to God by participation, for he is his own being, as we proved in the first book.¹ Therefore, he is his own power.

Moreover. Active power belongs to a thing’s perfection, as stated above.¹ Now every perfection of God is contained in his very being, as was shown in the first book.² Therefore, the divine power is not other than his very being. Now God is his own being, as we proved in the first book.³ Therefore, he is his own power.

Again. In those things whose powers are not their substance, their powers are accidents: hence natural power is placed in the second species of accident.¹ But in God there can be no accident, as was proved in the first book.² Therefore, God is his own power.

That God’s power is his action

From this we can show that God’s power is not other than his action.

For things that are identical with one and the same thing, are identical with one another.¹ Now God’s power is his substance, as we have proved,² and his action is also his substance, as we showed in the first book³ with regard to his intellectual operation: for this applies equally to his other operations. Therefore, in God power is not distinct from action.

Again. The action of a thing is a complement of its power: for it is compared to power as second act to first. Now the divine power is not completed by another than himself, since it is God’s very essence.¹ Therefore, in God power is not distinct from action.

Moreover. Just as active power is something acting, so is its essence something being. Now God’s power is his essence, as we have proved.¹ Therefore, his action is his being. But his being is his substance.² Therefore, God’s action is his substance, and so the same conclusion follows as before.

Further. An action that is not the substance of the agent is in the agent as an accident in its subject: therefore, action is reckoned among the nine predicaments of accident.¹ Now there can be nothing accidental in God.² Therefore, God’s substance is not other than his power.

In what way power is ascribed to God

Since, however, nothing is its own principle, and God’s action is not other than his power,¹ it is clear from the foregoing that power is ascribed to God not as the principle of action, but as the principle of the thing made. And since power implies relation to something else under the aspect of its principle—for active power is the principle of acting on something else, according to the Philosopher in Metaphysics 5²—it is evident that power is ascribed to God in relation to things made, according to reality, and not in relation to action, except according to our way of understanding, insofar as our intellect considers both (the divine power and action) by different concepts. Therefore, if certain actions are becoming to God which do not pass into something made but remain in the agent, power is not ascribed to God in their respect, except according to our manner of understanding, and not according to reality. Such actions are intelligence and volition. Accordingly, God’s power, properly speaking, does not regard such actions, but only their effects. Consequently, intellect and will are in God not as powers, but only as actions.

It is also clear from the foregoing that the manifold actions ascribed to God, as intelligence, volition, the production of things, and the like, are not so many different things, since each of these actions in God is his own very being, which is one and the same thing. How one thing may remain true while having many significations may be clearly seen from what has been shown in the first book.¹

That something is said of God in relation to creatures

Now as power is becoming to God in relation to his effects,¹ and as power conveys the notion of a principle, as we have stated;² and since principle denotes relationship to that which proceeds from it, it is evident that something can be said of God relatively, in relation to his effects.

Again. It is inconceivable that one thing be referred to another, unless conversely the latter be referred to it. Now we speak of other things in relation to God; for example, as regards their being which they have from God they are dependent upon him, as already proved.¹ Therefore, conversely we may speak of God in relation to creatures.

Further. Likeness is a kind of relation. Now God produces something like himself,¹ even as do other agents. Therefore, something is said of him relatively.

Moreover. Knowledge denotes relation to the thing known. Now God has knowledge not only of himself, but also of other things.¹ Therefore, something is said of God in relation to other things.

Again. Mover implies relation to thing moved, and agent to thing done. Now God is an agent, and an unmoved mover, as already proved.¹ Therefore, relations are predicated of him.

Again. First implies some kind of relation, and so does supreme. Now it was proved in the first book,¹ that he is the first being and the highest good.

It is, therefore, evident that many things are said of God relatively.

That relations said of God in reference to creatures are not really in God

These relations however which refer to his effects cannot possibly be in God.

For they cannot be in him as accidents in a subject, since no accident is in him, as we proved in the first book.¹ Neither can they be God’s very substance, because, since relative terms are those which essentially refer somehow to something else, as the Philosopher says in the Categories,² it would follow that God’s substance is essentially referred to something else. Now that which is essentially referred to another depends in some way on it, since it can neither exist nor be understood without it. Hence it would follow that God’s substance is dependent on something else outside it: thus it would not be of itself necessary being, as we have proved in the first book.³ Therefore, such relations are not really in God.

Again. It was proved in the first book¹ that God is the first measure of all beings. Therefore, God is compared to other beings as knowable things to our knowledge, since opinion or speech is true or false according as a thing is or is not, according to the Philosopher in the Categories.² Now, though a thing is said to be knowable in relation to knowledge, the relation is not really in the knowable, but only in the knowledge: hence, according to the Philosopher, in Metaphysics 5, the knowable is so called relatively, not because it is itself related, but because something else is related to it.³ Therefore, the said relations are not really in God.

Further. The aforesaid relations are said of God not only with respect to those things that are actual, but also with respect to those that are in potency, because he both has knowledge of them, and in reference to them is called the first being and the highest good. But that which is actual has no real relation to that which is not actual but potential, otherwise it would follow that there are actually an infinite number of relations in the same subject, since potentially infinite numbers are greater than the number two, which is prior to them all. Now God is not related to actual things otherwise than to potential things, for he is not changed by the fact that he produces certain things.¹ Therefore, he is not related to other things by a relation really existing in him.

Moreover. Whatever receives something anew must be changed, either essentially or accidentally. Now certain relations are said of God anew (for instance, that he is Lord or governor of a thing which begins anew to exist). Therefore, if a relation were predicated of God as really existing in him, it would follow that something accrues to God anew, and consequently that he is changed either essentially or accidentally: the contrary of which was proved in the first book.¹

How the aforesaid relations are predicated of God

Nevertheless, it cannot be said that the aforesaid relations exist extraneously as something outside God.

For, since God is the first being and highest good,¹ it would be necessary to consider yet other relations of God to those relations that are realities. And if these also are realities, we shall again have to find third relations, and so on indefinitely. Therefore, the relations by which God is referred to other things are not really existing outside God.

Again. A thing is predicated denominatively in two ways. For a thing may be denominated from that which is outside it (for instance, a person is said to be “somewhere” from place, and “sometime” from time), and a thing may be denominated from that which is in it (as a person is denominated “white” from whiteness). On the other hand, a thing is not found to be denominated from a relation as extraneous, but as inherent: for a man is not denominated a father except from fatherhood, which is in him. Therefore, it is impossible for the relations by which God is referred to creatures to be realities outside him.

Since, then, it has been proved¹ that they are not really in him, and yet are predicated of him,² it remains that they are ascribed to him according only to our way of understanding, from the fact that other things are referred to him. For our intellect, in understanding one thing to be referred to another, understands at the same time that the latter is related to the former, although sometimes it is not really related at all.

Therefore, it is also evident that the aforesaid relations are not said of God in the same way as other things predicated of God. For all other things—like wisdom and will—predicate his essence, whereas the aforesaid relations predicate minimally, but solely according to our way of understanding. And yet our understanding is not false. For from the very fact that our intellect understands that the relations of the divine effects terminate in God himself, it predicates certain things of him relatively: even so we understand and express the knowable relatively from the fact that our knowledge is referred to it.

Continuation of the foregoing

It is also clear from the foregoing that it is not prejudicial to God’s simplicity if many relations are predicated of him although they do not signify his essence, for they are consequent upon our way of understanding. For nothing hinders our intellect understanding many things, and being referred in many ways to that which is in itself simple, so as thus to consider the simple thing under a manifold relationship. And the more simple a thing is, the greater its virtue, and of so many more things is it a principle, and consequently it is understood as related in so many more ways. Thus a point is a principle of more things than a line is, and a line of more things than a surface. Therefore, the very fact that many things are said of God relatively bears witness to his supreme simplicity.

That God is the cause of being to all things

Now, since we have proved¹ that God is the source of being to some things, we must further show that everything besides himself is from him.

For whatever belongs to a thing not as such belongs to it through some cause, as white to a man, because that which has no cause is something first and immediate, and thus it must belong to the thing essentially and as such. Now it is impossible for any one thing to belong to two things, and to both of them as such. For that which is said of a thing as such does not go beyond that thing: for instance, to have three angles equal to two right angles does not go beyond a triangle. Accordingly, if something belongs to two things, it will not belong to both as such: hence it is impossible for any one thing to be predicated of two so as to be said of neither by reason of a cause. Rather it is necessary that either one be the cause of the other—for instance, fire is the cause of heat in a mixed body, and yet each is called hot—or else some third thing must be cause of both—for instance, fire is the cause of two candles giving light. Now “being” is said of everything that is. Therefore, it is impossible that there be two things, neither of which has a cause of its being; but either both the things in question must have their being through a cause, or else the one must be the cause of being to the other. Hence everything that exists in any way whatever must be from that to which nothing is a cause of being. Now, we have proved above¹ that God is this being to which nothing is a cause of its being. Therefore, from him is everything that is in any way whatever. If, however, it be said that “being” is not a univocal predicate, the above conclusion follows none the less. For it is not said of many equivocally, but analogically: and thus it is necessary to be brought back to one thing.

Moreover. That which belongs to a thing by its nature, and not by some other cause, cannot be diminished and deficient therein. For if something essential be subtracted from or added to a nature, there will be at once another nature, even as it happens in numbers, where the addition or subtraction of unity changes the species.¹ And if the nature or quiddity of a thing remain entire, although something is found to be diminished, it is clear that this does not depend simply on that nature, but on something else, through the absence of which it is diminished. Therefore, that which belongs to one thing less than to others belongs to it not through its nature alone, but through some other cause. Consequently, that thing will be the cause of all in a certain genus, to which thing the predication of that genus belongs above all: hence that which is most hot is seen to be the cause of heat in all things hot, and that which is most light is the cause of all things that have light. Now God is being above all, as we have proved in the first book.² Therefore, he is the cause of all of which “being” is predicated.

Further. The order of causes must correspond to the order of effects, since effects are proportionate to their causes.¹ Therefore, just as proper effects are reduced to their proper causes, so what is common in proper effects must be reduced to some common cause: thus the sun is the universal cause of generation above the particular causes of the generation of this or that thing, and the king is the universal cause of government in his kingdom, above the wardens of the kingdom and of each city. Now being is common to all. Therefore, above all causes there must be a cause to which it belongs to give being. But God is the first cause, as shown above.² Therefore, it follows that all things that exist are from God.

Again. That which is said through the essence of something is the cause of all that are so by participation: thus fire is the cause of all things ignited as such. Now God is being by his essence, because he is being itself.¹ In contrast, everything else is being by participation, for there can be but one being that is its own being, as was proved in the first book.² Therefore, God is the cause of being to all other things.

Moreover. God is the maker of a thing inasmuch as he is in act, as we have proved above.¹ Now, by his act and perfection he contains all the perfections of things, as we have shown in the first book,² and thus he is virtually all things. Therefore, he is the maker of all. But this would not be if something else were of a nature to be otherwise than from him: for nothing is of a nature to be from another and not to be from another, since if it be of a nature not to be from another, it is of itself necessary to be, and thus can never be from another. Therefore, nothing can be except from God.

Again. The imperfect originate from the perfect, as seed from an animal. Now God is the most perfect being and the highest good, as was shown in the first book.¹ Therefore, he is to all things the cause of being, especially since it was proved² that there can be but one such thing.

This is confirmed by divine authority. For it is said in the Psalm: who made heaven and earth, the sea, and all that is in them (Ps 146[145]:6); and: all things were made through him, and without him was not anything made that was made (John 1:3); and: from him and through him and to him are all things. To him be glory forever (Rom 11:36).

This sets aside the error of the ancient physicists, who asserted that certain bodies had no cause of their being, as well as that of some who say that God is not the cause of the substance of heaven, but only of its movement.

That God brought things into being out of nothing

From this it is clear that God brought things into being out of no preexisting thing as matter.

For if a thing is an effect of God, either something exists before it, or not. If not, our point is proved, namely, that God produces an effect from no preexisting thing. If, however, something exists before it, we must either go on to infinity—which is impossible in natural causes, as the Philosopher proves in Metaphysics 2¹—or we must come to some first thing that presupposes no other. And this can only be God. For it was shown in the first book² that he is not the matter of any thing, nor can there be anything other than God the being of which is not caused by God, as we have proved.³ It follows, therefore, that God in producing his effects requires no preexisting matter out of which to produce his work.

Further. Every matter is constricted to some particular species by an introduced form. Thus, to produce an effect out of preexisting matter by enduing it with a form in any way belongs to an agent that aims at some particular species. Now a like agent is a particular agent, since causes are proportionate to their effects.¹ Therefore, an agent that requires of necessity preexisting matter out of which to work its effect is a particular agent. But God is an agent as the universal cause of being, as was proved above.² Therefore, he needs no preexisting matter in his action.

Again. The more universal an effect, the higher its proper cause, because the higher the cause, to so many more things does its virtue extend. Now “to be” is more universal than “to be moved,” since some beings are immovable, as also philosophers teach (for instance stones and the like). It follows, therefore, that above the cause which acts only by causing movement and change, there is that cause which is the first principle of being, and we have proved¹ that this is God. Therefore, God does not act merely by causing movement and change. Now everything that cannot bring things into being save from preexisting matter acts only by causing movement and change, since to make something out of matter is the result of movement or change of some kind. Consequently, it is not impossible to bring things into being without preexisting matter. Therefore, God brings things into being without preexisting matter.

Moreover. Every agent produces something like itself in some way. Now every agent acts according as it is actually. Consequently, to produce an effect by causing in some way a form inherent to matter, will belong to that agent which is actualized by a form inherent to it, and not by its whole substance. Hence the Philosopher proves in Metaphysics 7¹ that material things, which have forms in matter, are engendered by material agents that have forms in matter, and not by essentially existing forms. Now God is actual being not by a form inherent to him, but by his whole substance, as we have proved above.² Therefore, the proper mode of his action is to produce a whole subsistent thing, and not merely an inherent thing (namely, a form in matter). And every agent that requires no matter for its action acts in this way. Therefore, God requires no preexisting matter in his action.

Further. Matter is compared to an agent as the recipient of the action proceeding from the agent: for the action, which is the agent’s as proceeding from it, is the patient’s as residing in it. Therefore, matter is required by an agent that it may receive the agent’s action, since the agent’s action received in the patient is the patient’s act and form, or some beginning of a form in it. Now God does not act by an action that must be received in a patient, because his action is his substance, as already proved.¹ Therefore, he requires no preexisting matter in order to produce an effect.

Again. Of different things there are different matters: for the matter of spiritual things is not the same as that of corporeal things, nor that of heavenly bodies the same as that of corruptible bodies. This is evident from the fact that receptivity as a property of matter is not of the same kind in the aforesaid. For receptivity in spiritual things is intelligible. Thus the intellect receives the species of intelligible objects, but not according to their material being, while heavenly bodies receive newness of situation, but not newness of being, as lower bodies do. Therefore, there is not one matter that is in potency to universal being. But God’s activity regards all being universally.¹ Therefore, no matter corresponds proportionately to him. Therefore, he does not require matter of necessity.

Moreover. Wherever certain things in the universe are in mutual proportion and order, one of them must proceed from the other, or both from some one. For order must be founded in one by its corresponding with another: otherwise order or proportion would be the result of chance, which is inadmissible in the first principles of things, because it would follow yet more that all else are from chance.¹ If, then, there be any matter proportionate to the divine action, it follows that either the one is from the other, or both from a third. But since God is the first being and the first cause,² he cannot be the effect of matter, nor can he be from any third cause. Therefore, it follows that if there be matter proportionate to God’s action, he is the cause of it.

Again. That which is the first of beings must be the cause of the things that are: for if they were not caused they would not be set in order by it, as we have already proved.¹ Now there is this order between act and potency: that, although in the one and same thing which is sometimes in potency and sometimes in act, potency precedes act in point of time, whereas act precedes by nature, act must nevertheless precede potency simply speaking, which is evidenced by the fact that potency is not reduced to act save by a being in act. But matter is a being in potency. Therefore, God, who is pure act, must be simply prior to matter, and consequently the cause of it. Therefore, matter is not necessarily presupposed for his action.

Again. Prime matter is in some way, for it is a being in potency. Now God is the cause of all things that are, as we have proved.¹ Therefore, God is the cause of prime matter, to which nothing is preexistent. Therefore, the divine action needs no preexisting nature.

Divine Scripture confirms this truth, saying: in the beginning God created heaven and earth (Gen 1:1). For to create is nothing else than to bring something into being without preexisting matter.

By this is refuted the error of the ancient philosophers who asserted that matter has no cause whatever, because they observed that in the actions of particular agents something is always preexisting to action: thus they drew the opinion common to all that from nothing, nothing is made.¹ This is true in particular agents. But they had not yet arrived at the knowledge of the universal agent, which is the active cause of all being, and of necessity presupposes nothing for his action.

That creation is neither movement nor change

Having proved the foregoing, it is evident that God’s action, which is without preexisting matter and is called creation, is neither movement nor change, properly speaking.

For all movement or change is the action of that which is in potency as such.¹ Now in this action there preexists nothing in potency to receive the action, as we have proved.² Therefore, it is neither movement nor change.

Again. The extremes of a movement or change are included in the same order: either because they come under one genus as contraries (for instance, in the movement of growth and alteration, and when a thing is carried from one place to another); or because they have one potency of matter in common, as privation and form in generation and corruption. But neither of these applies to creation: for it admits of no potency, nor of anything of the same genus that may be presupposed to creation, as we have proved.¹ Therefore, there is neither movement nor change in it.

Further. Movement and change must precede that which is made by change or movement, because having been made is the beginning of rest and the term of movement. Therefore, all change must be movement or the term of a movement that is successive. For this reason, what is being made is not. For as long as movement lasts, something is being made and is not. In contrast, in the term itself of movement (in which rest begins), a thing is no longer being made, but it has been made. Now in creation this is impossible: for if creation preceded as movement or change, it would necessarily presuppose a subject, and this is contrary to the nature of creation. Therefore, creation is neither movement nor change.

How to solve the objections against creation

From this we may see the vacuity of those who gainsay creation by arguments taken from the nature of movement and change, such as that creation must take place in some subject (like other movements and changes) and that it implies the transmutation of non-being into being (like that of fire into air).

For creation is not a change, but the very dependence of created being on the principle whereby it is produced. Hence it is a kind of relation. Therefore, nothing prevents its being in the creature as its subject.

Nevertheless, creation seems to be a kind of change only according to our way of understanding: insofar, to wit, as our intellect grasps one and the same thing as previously nonexistent, and as afterwards existing.

It is clear, however, that if creation is a relation, it is a thing, and neither is it uncreated, nor is it created by another relation. For, since a created effect depends really on its creator, this relation must be some thing. Now everything is brought into being by God.¹ Therefore, it receives its being from God. And yet it is not created by a different creation from the first creature which is stated to be created thereby. Because accidents and forms, just as they do not exist by themselves, so neither are they created by themselves (since creation is the production of a being), but just as they are in another, so are they created when other things are created.

That in creation there is no succession

It is also clear from the foregoing that all creation is without succession.

For succession is proper to movement. But creation is not a movement, nor the term of a movement, as change is.¹ Therefore, there is no succession in it.

Again. In every successive movement there is some mean between its extremes: for a mean is that which a continuously moved thing reaches first before reaching the term.¹ Now between being and non-being, which are as the extremes of creation, no mean is possible. Therefore, there is no succession in it.

Moreover. In every making in which there is succession, a thing is becoming before it has been made, as is proved in Physics 6.¹ Now this cannot happen in creation, because the becoming, which would precede being made, would need a subject. And this could not be the creature itself whose creation is in question, since it is not before it is made. Nor would it be in the maker, because to be moved is the act not of the mover, but of the thing moved.² It follows that becoming would have for its subject some preexisting matter of the thing made. But this is incompatible with creation.³ Therefore, there can be no succession in creation.

Further. Every making that proceeds by succession must take time, since before and after in movement are reckoned by time.¹ Now time, movement, and the thing subject to movement are all simultaneously divided.² This is evident in local movement: for that which is moved with regularity passes through half a magnitude in half the time. Now the division in forms that corresponds to division of time is according to intensity and remissness: thus if a thing is heated to such a degree in so much time, it is heated to a lesser degree in less time. Accordingly, succession in any movement or making is possible according as the thing in respect of which there is motion is divisible: either according to quantity, as in local movement and increase; or according to intensity and remission, as in alteration. Now the latter occurs in two ways. First, because the form which is the term of movement is divisible in respect of intensity and remission, as when a thing is in motion towards whiteness. Second, because such a division happens in dispositions to such a form: thus the becoming of fire is successive on account of the previous alteration as regards the dispositions to the form. But the substantial being itself of a creature is not divisible in this way, for substance cannot be more or less.³ Nor do any dispositions precede creation, since there is no preexisting matter: for disposition is on the part of matter. It follows, therefore, that there cannot be succession in creation.

Hence divine Scripture declares that the creation of things took place in an indivisible instant, when it says: in the beginning God created the heavens and the earth (Gen 1:1): which beginning Basil expounds as the beginning of time,¹ and this must be indivisible, as is proved in Physics 6.²

That no body can create

Hence it is evident that no body can produce anything by creation.

For no body acts unless it be moved, since agent and patient must be together, as also maker and that which is made: and those things are together which are in the same place, as stated in Physics 5,¹ and a body does not acquire a place except by movement. But no body is moved except in time. Therefore, whatever is done by the action of a body is done successively, whereas creation, as we have proved,² is without succession. Therefore, nothing can be produced by way of creation by any body whatever.

Again. Since agent and effect must be like each other, a thing cannot produce the whole substance of the effect, unless it act by its entire substance; thus the Philosopher proves conversely, in Metaphysics 7,¹ that if a form without matter acts by its whole self, it cannot be the proximate cause of generation, in which the form alone is brought into act. Now no body acts by its whole substance, although the whole of it acts: for, since every agent acts by the form whereby it is actual, only a thing whose whole substance is a form can act by its whole substance. And this can be said of no body, because every body has matter, since every body is changeable. Therefore, no body can produce a thing as to the whole substance of that thing, and this is essential to creation.

Further. To create belongs exclusively to an infinite power. For an agent’s power is so much the greater, according as it is able to bring into act a potency more distant from act (for instance, that which can produce fire from water in comparison with that which can produce it from air). Hence where preexisting potency is altogether removed, all proportion to a determinate distance is surpassed; and thus the power of an agent that produces something without any preexisting potency, must surpass all conceivable proportion to the power of an agent that produces something out of matter. But no power of a body is infinite, as the Philosopher proves in Physics 8.¹ Therefore, no body can create a thing, for this is to make something out of nothing.

Moreover. Mover and moved, maker and made must be together, as proved in Physics 7.¹ Now a bodily agent cannot be present to its effect except by contact, by which the extremes of contiguous things come together.² Hence it is impossible for a body to act save by contact. But contact is of one thing in relation to another. And thus where there is nothing preexistent besides the agent, as happens in creation, there can be no contact. Therefore, no body can act by creating.

Thus we may see the falseness of the position of those who say that the substance of the heavenly bodies causes the matter of the elements, since matter can have no cause except that which acts by creating, because matter is the first subject of movement and change.

That it belongs to God alone to create

It can also be shown from the foregoing that creation is an action proper to God, and that he alone can create.

For, since the order of actions is according to the order of agents (because the more excellent the agent, the more excellent the action), it follows that the first action is proper to the first agent. Now creation is the first action, since it presupposes no other, while all others presuppose it. Therefore, creation is the proper action of God alone, who is the first agent.¹

Again. It was proved that God creates things from the fact that there can be nothing besides himself that is not created by him.¹ Now this cannot be said of anything else, because nothing else is the universal cause of being. To God alone, therefore, does creation belong as his proper action.

Further. Effects correspond proportionately to their causes, namely, so that we ascribe actual effects to actual causes, and potential effects to potential causes. In like manner, we ascribe particular effects to particular causes, and universal effects to universal causes, as the Philosopher teaches in Physics 2.¹ Now being is the first effect, and this is evident by reason of its universality. Therefore, the proper cause of being is the first and universal agent, which is God. But other agents are the causes not of being simply, but of being this (for example, of being a man, or of being white). But being simply is caused by creation, which presupposes nothing, since nothing can preexist outside being simply. By other makings, this or such a being is made, because this or such a being is made from an already existing being. Therefore, creation is God’s proper action.

Moreover. Whatever is caused with respect to some particular nature cannot be the first cause of that nature, but only a second and instrumental cause. For Socrates, since he has a cause of his humanity, cannot be the first cause of human nature because, seeing that his human nature is caused by some one, it would follow that he is the cause of himself, since he is what he is by human nature. Consequently, a univocal generator must be like an instrumental agent in relation to that which is the primary cause of the whole species. Hence it is that all the lower active causes must be compared to the higher causes as instrumental to primary causes. Now every substance other than God has being caused by another, as was proved above.¹ Therefore, it is impossible for it to be a cause of being otherwise than as instrumental and as acting by virtue of another. But an instrument is never employed save in order to cause something by the way of movement: for the very notion of an instrument is that it is a mover moved. Creation, however, is not movement, as we have proved.² Therefore, no substance besides God can create anything.

Again. An instrument is employed on account of its being adapted to the effect, that it may be a medium between the first cause and the effect, and be in contact with both, and thus the influence of the first reaches the effect through the instrument. Hence there must be something that receives the influence of the first, in that which is caused by the instrument. But this is contrary to the nature of creation, since it presupposes nothing. It follows, therefore, that nothing besides God can create, neither as principal agent nor as instrument.

Again. That which is caused in respect of some nature cannot be the cause of that nature simply, for it would be its own cause, but it can be the cause of that nature in this individual. Thus Plato is the cause of human nature in Socrates, but not simply, since he is himself caused in respect of human nature. Now that which is the cause of something in this individual communicates the common nature to some particular thing by which that nature is specified or individualized. But this cannot be by creation, which presupposes nothing to which something can be communicated by an action. Therefore, it is impossible for anything created to be the cause of something else by creation.

Moreover. Since every agent acts insofar as it is actual, it follows that the mode of action must follow the mode of a thing’s act: therefore the hot thing which is more actually hot gives greater heat. Consequently, anything whose act is determined to genus, species, and accident must have a power determined to effects like the agent as such, since every agent produces its like. Now nothing that has determinate being can be like another of the same genus or species except in the point of genus or species, for insofar as it is this particular thing, one particular thing is distinct from another. Nothing, therefore, that has a finite being, can by its action be the cause of another, except as regards its having genus or species—not as regards its subsisting as distinct from others. Therefore, every finite agent presupposes before its action that by which its effect subsists as an individual. Therefore, it does not create: and this belongs exclusively to an agent whose being is infinite, and which contains in itself the likeness of all beings, as we have proved above.¹

Again. Since whatever is made, is made that it may be, if a thing is said to be made that was before, it follows that it is not made in itself but accidentally. But that is made in itself which was not before. Thus, if from white a thing is made black, a black thing is made and a colored thing is made, but black in itself, because it is made from not-black, and colored accidentally, since it was colored before. Accordingly, when a being is made, such as a man or a stone, a man is made in himself, because he is made from not-man; but a being is made accidentally, since he is not made from non-being simply, but from this particular non-being, as the Philosopher says in Physics 1.¹ When, therefore, a thing is made from non-being simply, a being is made in itself. Therefore, it follows that it is made by that which is in itself the cause of being, since effects are referred to their proportionate causes. Now only the first being is the cause of a being as such, while other things are causes of being accidentally, and of this particular being in itself. Since, then, to produce a being from no preexisting being is to create, it follows that it belongs to God alone to create.

The authority of Sacred Scripture bears witness to this truth, for it declares that God created all things: in the beginning God created the heavens and the earth (Gen 1:1). And Damascene says: all those who say that the angels are creators of any substance whatsoever are children of their father the devil; for those who are creatures are not creators.¹ Hereby is refuted the error of certain philosophers who said that God created the first separate substance, by whom the second was created, and so on, in a certain order, to the last.²

That God can do all things

Hence it is clear that the divine power is not determined to one particular effect.

For if it belongs to God alone to create, it follows that whatever things cannot be produced by their cause save by way of creation must be immediately produced by him. Now such are all separate substances (which are not composed of matter and form, and the existence of which we will suppose for the present),¹ and likewise all corporeal matter. These things then, being distinct from one another, are the immediate effect of the aforesaid power. Now no power that produces immediately a number of effects not from matter is determined to one effect. I say “immediately,” because if it produced them through intermediaries, the diversity might be owing to the intermediary causes. And I say “not from matter,” because the same agent by the same action causes different effects according to the diversity of matter; thus the heat of fire hardens clay and melts wax. Therefore, God’s power is not determined to one effect.

Again. Every perfect power extends to all those things to which its essential and proper effect can extend: thus the art of building, if perfect, extends to whatever can have the nature of a house. Now God’s power is the essential cause of being, and being is its proper effect, as stated above.¹ Therefore, it extends to all that is not incompatible with the notion of being: for if his power were confined to one effect alone, it would be the cause of a being, not as such, but as this particular being. Now the opposite of being, which is non-being, is incompatible with the notion of being. Therefore, God can do all things but those which include the notion of non-being, and such are those that imply a contradiction. It follows, therefore, that God can do whatever does not imply a contradiction.

Again. Every agent acts insofar as it is actual. Therefore, the mode of an agent’s power in acting follows its mode of act: for man begets man, and fire begets fire. Now God is perfect act, possessing in himself the perfections of all things, as was proved above.¹ Therefore, his active power is perfect, and extends to all things whatsoever that are not incompatible with the notion of act. But these are only those which imply a contradiction. Therefore, God can do everything except these things.

Moreover. To every passive potency there corresponds an active potency, since potency is for the sake of act, as matter for the sake of form. Now a being in potency cannot come to be in act save by the power of something in act. Thus potency would be without purpose were there no active power of an agent that could reduce it to act, and yet nothing in the things of nature is void of purpose. Thus we find that all things that are in the potency of matter in things subject to generation and corruption can be reduced to act by the active power which is in the heavenly body, which is the first active force in nature. Now just as the heavenly body is the first agent in regard to lower bodies, so God is the first agent in respect of all created being. Therefore, God can do everything is in the potency of created being by his active power. And all that is not incompatible with created being is in the potency of created being, just as whatever does not destroy human nature is in the potency of human nature. Therefore, God can do all things.

Now in none of these ways can any effect be withheld from the divine power. For nothing can be impossible to him on account of unlikeness in the effect, for everything is like him insofar as it has being, as we have proved above.¹ Nor again on account of the excellence of the effect, since it has been proved² that God is above all beings in goodness and perfection. Nor again on account of a defect in matter, since he is the cause of matter, which cannot be caused except by creation. Moreover, he needs no matter in acting, since he brings a thing into being without anything preexistent.³ Therefore, lack of matter cannot hinder his action from producing its effect.

It remains, therefore, that God’s power is not confined to any particular effect, but is able to do simply all things: and this means that he is almighty.

Hence also divine Scripture teaches this as a matter of faith. For it is said in the person of God: I am God Almighty; walk before me, and be perfect (Gen 17:1); and: I know that you can do all things (Job 42:2); and in the person of the angel: with God no word will be impossible (Luke 1:37).

By this is refuted the error of certain philosophers who asserted that only one effect was immediately produced by God, as though his power were confined to the production of it; and that God can only act according to the course of natural things. Of these it is said: who looked upon the Almighty as if he could do nothing (Job 22:17).

That God does not act of natural necessity

From this it may be proved that God acts among creatures not by necessity of his nature, but by the judgment of his will.

For the power of every agent that acts of natural necessity is confined to one effect. The consequence is that all natural things always happen in the same way, unless there be an obstacle, while voluntary things do not. Now the divine power is not directed to only one effect, as we have proved above.¹ Therefore, God acts not of natural necessity, but by his will.

Again. Whatever implies no contradiction is subject to the divine power, as we have proved.¹ Now many things are not among those created, which nevertheless would not imply a contradiction if they were. This is evident chiefly with regard to the number, quantities, and distances of the stars and other bodies, in which no contradiction would be implied if the order of things were different. Therefore, many things are subject to the divine power that are not found to exist actually. Now whoever does some of the things that he can do, and does not do others, acts by his will’s choice, and not by necessity of his nature. Therefore, God acts not of natural necessity, but by his will.

Again. Every agent acts according as the likeness of its effect is in it: for every agent produces its like. Now whatever is in something else is in it according to the mode of the thing in which it is. Since, then, God is intelligent by his essence, as we have proved,¹ it follows that the likeness of his effect is in him in an intelligible way. Therefore, he acts by his intellect. Now the intellect does not produce an effect except by means of the will, the object of which is an understood good, which moves the agent as his end. Therefore, God works by his will, and not by a necessity of his nature.

Moreover. According to the Philosopher in Metaphysics 9,¹ action is twofold: one which remains in the agent and is its perfection, for instance to see; the other, which passes into outward things and is a perfection of the thing done, as to burn in the case of fire. Now God’s action cannot belong to the kind of actions which are not in the agent, since his action is his substance, as already proved.² Therefore, it must be of that kind of actions which are in the agent, and are as a perfection thereof. But the like are only the actions of one who has knowledge and appetite. Therefore, God works by knowing and willing, and consequently not by a necessity of his nature, but by the judgment of his will.

Further. That God works for an end can be evident from the fact that the universe is not the result of chance, but is directed to a good, as stated by the Philosopher in 12 Metaphysics.¹ Now the first agent for an end must be an agent by intellect and will, because things devoid of intellect work for an end as directed to the end by another. This is evident in things done by art: for the flight of the arrow is directed towards a definite mark by the aim of the archer. And so likewise must it be in the works of nature. For in order that a thing be rightly directed to a due end, it is necessary that one know the end itself, and the means to that end, as also the due proportion between both, and this belongs only to an intelligent being. Since, therefore, God is the first agent, he works not by a necessity of his nature, but by his intellect and will.

Again. The first action belongs to the first agent, as the first movement to the first movable. Now, the action of the will naturally precedes the action of nature, because the more perfect is naturally first, although in some particular thing it may be last in time. Now the action of a voluntary agent is more perfect, a proof of which is that among us agents which act by will are more perfect than those which act by natural necessity. Therefore, to God, who is the first agent, is due that action which is by the will.

Further. The same is evident from the fact that where both actions are united, the power which acts by will is above that which acts by nature, and uses the latter as an instrument, for in man the intellect (which acts by the will) is higher than the vegetative soul (which acts by a necessity of its nature). Now the divine power is above all beings. Therefore, it acts on all things by will, not by natural necessity.

Again. The will has for its object a good considered as a good, but nature does not compass the idea of good in general, but the particular good which is its perfection. Since, then, every agent acts insofar as it intends a good (because the end moves the agent), it follows that the agent by will is compared to the agent by natural necessity as a universal to a particular agent. Now the particular agent is compared to the universal agent, as posterior to it, and as its instrument. Therefore, the first agent must be voluntary and not an agent by natural necessity.

Divine Scripture teaches us this truth. For it is said in the Psalm: whatever the Lord pleases he does (Ps 135[134]:6), and: who accomplishes all things according to the counsel of his will (Eph 1:11).

Hilary also in his book On Synods (no. 58) says: God’s will gave substance to all creatures. And further on: all things were created such as God willed them to be.

Hereby also is refuted the error of certain philosophers who asserted that God works by natural necessity.

That God works according to his wisdom

From the foregoing it is clear that God produces his effects according to his wisdom.

For the will is moved to act by some kind of apprehension, since the apprehended good is the object of the will. Now God is a voluntary agent, as we have proved.¹ Since, then, in God there is none but intellectual apprehension, and since he understands nothing except by understanding himself,² to understand whom is to be wise, it follows that God works according to his wisdom.

Again. Every agent produces its like. Hence it follows that every agent works by that according to which it bears a likeness to its effect: thus fire heats according to the mode of its heat. Now in every voluntary agent, as such, the likeness to its effect is in respect of the apprehension of its intellect; for if the likeness to its effect were in a voluntary agent according only to the disposition of its nature, it would only produce one effect, since the natural reason of one is only one. Therefore, every voluntary agent produces an effect according to the reason of its intellect. Now God works by his will, as already proved.¹ Therefore, he brings things into being by the wisdom of his intellect.

Moreover. According to the Philosopher, in Metaphysics 1, it belongs to a wise man to set things in order.¹ For the ordering of things cannot be done except by the knowledge of the things ordered as to their relation and proportion both to one another and to something higher, which is their end, since the mutual order of certain things is on account of their order to the end. Now knowledge of the mutual relations and proportions of certain things belongs only to one who has an intellect, while it belongs to wisdom to judge of certain things by the highest cause.² It follows, then, that all ordering is done by the wisdom of an intelligent being. Thus in mechanics those who direct the order of buildings are called the wise men of the building craft. Now the things produced by God have a mutual order which is not casual, as it is the same always or for the most part. Hence it is evident that God brought things into being by ordering them. Therefore, God brought things into being by his wisdom.

Further. Things that proceed from the will are either things that may be done (such as acts of virtue, which are the perfections of the doer), or they pass into outward matter, and are things that can be made. It is clear, then, that created things proceed from God as made. Now the reason about things to be made is art, as the Philosopher says.¹ Therefore, all created things are compared to God as products of art to the craftsman. But the craftsman brings his handiwork into being by the ordering of his wisdom and intellect. Therefore, God also made all creatures by the ordering of his intellect.

This is confirmed by divine authority: for it is said in the Psalm: in wisdom have you made them all (Ps 104[103]:24), and: the Lord by wisdom founded the earth (Prov 3:19).

Hereby is set aside the error of some who said that all things depend on God’s simple will without any reason.¹

How the Almighty is said to be unable to do certain things

From the foregoing we may gather that though God is almighty, he is nevertheless said to be unable to do certain things. For it was shown above¹ that in God there is active potency (while it had already been proved in the first book² that there is no passive potency in him), whereas we are said “to be able” in respect of either potency. Thus God is unable to do those things the possibility of which belongs to passive potency. What such things are must be the subject of our inquiry.

In the first place, then, active potency is directed to action, while passive potency is directed to being. Consequently, potency to being is only in those things which have matter subject to contrariety. Since, therefore, passive potency is not in God, he is unable as regards anything that pertains to his being. Therefore, God cannot be a body, and so forth.

Again. The act of this passive potency is movement.¹ Therefore, God, to whom passive potency is unbecoming, cannot be changed.

It may be further concluded that he cannot be changed in respect of each kind of movement (for instance, that he cannot be increased, nor diminished, nor altered, nor generated, nor corrupted).

Moreover. Since to fail is a kind of corruption, it follows that he is unable to fail in anything.

Again. Since weariness results from defect of power, and forgetfulness from defect of knowledge, it is clear that he can neither be weary nor forget.

Moreover. Nor can he be overcome or suffer violence. For these things only happen to those things that are of a movable nature.

Likewise, he can neither repent, nor be angry, or sorrowful, since all these denote passion and defect.

Again. Since the object and effect of an active potency is something made, and since no potency is operative, if the ratio of object be lacking—thus the sight sees not if the actually visible be lacking—it follows that God is unable to do whatever is contrary to the ratio of being as being, or of being made insofar as it is made. We must inquire what these things are.

In the first place, that which destroys the ratio of being is contrary to the ratio of being. Now the ratio of being is destroyed by the opposite of being, as the ratio of man is destroyed by the opposite of man or of his parts. Now the opposite of being is non-being. Consequently, God is unable to do this, so as to make the one and same thing to be and not to be at the same time, which is for contradictories to be simultaneous.

Again. Contradiction is included in contraries and privative opposites: for to be white and black is to be white and not white, and to be seeing and blind is to be seeing and not seeing. Hence it amounts to the same that God is unable to make opposites to be simultaneously in the same subject and in the same respect.

Moreover. The removal of an essential principle of a thing implies the removal of the thing itself. If, then, God cannot make a thing at the same time to be and not to be, neither can he make a thing to lack any of its essential principles while the thing itself remains (for instance, that a man have no soul).

Hence it is also evident that God cannot make the past not to have been. For this also includes a contradiction, since it is equally necessary for a thing to be while it is, and to have been while it was.

There are also some things which are incompatible with the ratio of being made as made. God cannot do these also, since whatever God makes must be something made.

Hence it is evident that God cannot make God. For it belongs to the ratio of being made that its being depends on another cause. And this is contrary to the ratio of that which we call God, as is evident from the foregoing.¹

For the same reason God cannot make a thing equal to himself. Because a thing whose being does not depend on another is greater in being and other excellencies than that which depends on another, which belongs to the ratio of a thing made.

Likewise, God cannot make a thing to be preserved in being without himself. For the preservation of a thing in being depends on its cause. Therefore, if the cause be removed, the effect must be removed. Consequently, if there could be a thing that is not preserved in being by God, it would not be his effect.

Again. Since he is an agent by will,¹ he cannot do those things which he cannot will. Now we may realize what he cannot will if we consider how it is possible for necessity to be in the divine will, since what is of necessity is impossible not to be, and what is impossible to be, necessarily is not.

It is, therefore, evident that God cannot make himself not to be, or not to be good or happy, because he necessarily wills himself to be, and to be good and happy, as we proved in the first book.¹

Again, it was shown above¹ that God cannot will anything evil. Therefore, it is evident that God cannot sin.

Likewise, it was proved above¹ that God’s will cannot be changeable. Consequently, it cannot make that which is willed by him not to be fulfilled.

It must, however, be observed that he is said to be unable to do this in a different sense from that in which he is said to be unable to do the things mentioned before. For God is simply unable either to will or to make the foregoing, but God can do or will these, if we consider his power or will absolutely, but not if we presuppose him to will the opposite. For the divine will, in respect of creatures, has no necessity except on a supposition, as we proved in the first book.¹ Hence all such statements as “God cannot do the contrary of what he has decreed to do,” and any like sayings are to be understood in the composite sense, for thus they imply a supposition of the divine will with regard to the opposite. But if they be understood in the divided sense, they are false, because they refer to God’s power and will absolutely.

And as God acts by will, so also does he act by intellect and knowledge, as we have proved.¹ Hence he cannot do what he has foreseen that he will not do, or omit to do what he has foreseen that he will do, for the same reason that he cannot do what he wills not to do, or omit to do what he wills. Also, each assertion is conceded and denied in the same sense, namely, that he be said to be unable to do these things, indeed not absolutely, but on a certain condition or supposition.

That the divine intellect is not confined to certain determined effects

Insofar as it has been proved¹ that the divine power is not limited to certain determined effects, and this because he acts not by a necessity of his nature, but by his intellect and will. Lest someone perhaps think that his intellect or knowledge can only reach to certain effects, and that consequently he acts by a necessity of his knowledge, although not by a necessity of his nature, it remains to be shown that his knowledge or intellect is not confined to any limits in its effects.

For it was proved above¹ that God comprehends all other things that can proceed from him by understanding his essence, in which all such things must necessarily exist by a kind of likeness, even as effects are virtually in their causes. If, then, the divine power is not confined to certain definite effects, as we have shown above,² it is necessary to pronounce a like opinion on his intellect.

Further. We have already proved¹ the infinity of the divine intellect. Now, no matter how many finite things we add together, even though there were an infinite number of finite things, we cannot equal the infinite, for it infinitely exceeds the finite, however great. Now it is clear that nothing outside God is infinite in its essence, since all else are by the very nature of their essence included under certain definite genera and species. Consequently, however many and however great divine effects be taken, it is always in the divine essence to exceed them, and so it can be the ratio of more. Therefore, the divine intellect, which knows the divine essence perfectly, as we have shown above,² surpasses all finitude of effects. Therefore, it is not necessarily confined to these or those effects.

Again. It was shown above¹ that the divine intellect knows an infinite number of things. Now God brings things into being by the knowledge of his intellect. Therefore, the causality of the divine intellect is not confined to a finite number of effects.

Moreover. If the causality of the divine intellect were confined to certain effects, as though it produced them of necessity, this would be in reference to the things which it brings into being. But this is impossible, for it was shown above¹ that God understands even those things that never are, nor shall be, nor have been. Therefore, God does not work by necessity of his intellect or knowledge.

Hence it is said in the Psalm: great is our Lord, and abundant in power; his wisdom is beyond measure (Ps 147[146]:5).

Through this, we set aside the opinion of certain philosophers who say that from the very fact that God understands himself, this particular disposition of things flows from him necessarily, as though he did not give each thing its limits, and all things their disposition by his own counsel, as the Catholic faith declares.

It is to be observed, however, that although God’s intellect is not confined to certain effects, yet he decides on certain determinate effects with a view to producing them ordinately by his wisdom. Thus it is said: but you have arranged all things by measure and number and weight (Wis 11:21).

That the divine will is not confined to certain effects

It may also be proved from the foregoing that neither is his will, by which he works, necessitated to produce certain determinate effects.

For the will must be proportionate to its object. Now the object of the intellect is a understood good, as stated above.¹ Hence the will has a natural aptitude to extend to whatever the intellect can propose to it under the aspect of good. If, then, the divine intellect is not confined to certain effects, as we have shown,² it follows that neither does the divine will produce certain determinate effects of necessity.

Creation in general

How there is anything due in the production of things

Again. From what has been said it may be shown that God in the creation of things did not work of necessity, as though he brought things into being as a debt of justice.

For justice, according to the Philosopher, in Ethics 5,¹ is towards another person to whom it renders his due. But nothing to which anything may be due is presupposed to the universal production of things. Therefore, the universal production of things could not result from a debt of justice.

Again. Since the act of justice is to render to each one that which is his own,¹ the act by which a thing becomes one’s own precedes the act of justice, as appears in human affairs: for a man by working has a right to call his own what is rendered to him, as an act of justice, by the person who pays him. Therefore, the act by which a person first acquires something of his own cannot be an act of justice. Now a created thing begins to have something of its own by creation. Therefore, creation does not proceed from a debt of justice.

Moreover. In every genus, that which is on account of itself precedes that which is on account of another. Consequently, that which is simply first of all causes is a cause on its own account only, whereas that which acts by reason of a debt of justice does not act on its own account only, for it acts on account of the thing to which the debt is due. Therefore God, since he is the first cause and the first agent,¹ did not bring things into being from a debt of justice.

Hence it is said: who has given a gift to him that he might be repaid? For from him and through him and to him are all things (Rom 11:35–36); and: who hath given me before that I should repay him? All things that are under heaven are mine (Job 41:2).

Hereby is refuted the error of some who strive to prove that God cannot do save what he does, because he cannot do except what he ought to do. For he does not produce things from a debt of justice, as we have proved.

Nevertheless, although nothing to which anything can be due precedes the universal creation of things, something uncreated precedes it, and this is the principle of creation. This may be considered in two ways. For the divine goodness precedes as the end and first motive of creation, according to Augustine, who says: because God is good, we exist.¹ Also his knowledge and will precede, as by them things are brought into being.

Accordingly, if we consider the divine goodness absolutely, we find nothing due in the creation of things. For in one way a thing is said to be due to someone on account of another person being referred to him, in that it is his duty to refer to himself that which he has received from that person. Thus it is due to a benefactor that he be thanked for his kindness, inasmuch as he who has received the kindness owes this to him. But this kind of due has no place in the creation of things, since there is nothing preexistent to which it can be competent to owe anything to God, nor does any favor of his preexist. In another way, something is said to be due to a thing in itself, since that which is required for a thing’s perfection is necessarily due to it. Thus it is due to a man to have hands or strength, since without these he cannot be perfect. Now God’s goodness needs nothing outside him for its perfection. Therefore, the production of creatures is not due to him by way of necessity.

Again. God brings things into being by his will, as we have shown above.¹ Now it is not necessary, if God wills his own goodness to be, that he should will other things than himself to be produced, because the antecedent of this conditional proposition is necessary, but not the consequent. For it was shown in the first book² that God necessarily wills his own goodness to be, but does not necessarily will other things. Therefore, the production of creatures is not necessarily due to the divine goodness.

Moreover. It has been proved¹ that God brings things into being neither by necessity of his nature, nor by necessity of his knowledge, nor by necessity of his will, nor by necessity of his justice. Therefore, by no manner of necessity is it due to the divine goodness that things be brought into being.

It may be said, however, that it is due to him by way of a certain becomingness. But justice properly speaking requires a debt of necessity, since what is rendered to someone out of justice is due to him by a necessity of right.

Accordingly, it cannot be said that the production of creatures arose either from a debt of justice whereby God is the creature’s debtor, or from a debt of justice whereby he is a debtor to his own goodness—if justice be taken in the proper sense. But if justice be taken in a broad sense, we may speak of justice in the creation of things insofar as the creation is becoming to the divine goodness.

If, however, we consider the divine ordinance whereby God decided by his intellect and will to bring things into being, then the production of things proceeds from the necessity of the divine ordinance.¹ For it is impossible that God should decide to do a certain thing which afterwards he did not, otherwise his decision would be either changeable or weak. It is, therefore, necessarily due to his ordinance that it be fulfilled. And yet this debt is not enough for the notion of justice, properly speaking, in the creation of things, in which we can consider nothing but the action of God in creating, and there is no justice properly speaking between one same person and himself, as the Philosopher says in Ethics 5.² Therefore, it cannot be said properly that God brought things into being from a debt of justice, for the reason that he ordained by his knowledge and will to produce them.

Continuation of the foregoing

If, however, we consider the production of a particular creature, it will be possible to find in it a debt of justice by comparing a subsequent creature to a preceding one. And I say preceding, not only in time but also in nature.

Accordingly, in those divine effects which were to be produced first, we find no debt, but in the subsequent production we find a debt, yet in a different order. For if those things that are first naturally are also first in being, those which follow become due on account of those which precede. For given the causes, it is due that they should have actions by which to produce their effects. On the other hand, if those which are first naturally are subsequent in being, then those which are first become due on account of those which come afterwards: thus it is due that medicine precede in order that health may follow. And in either case there is this in common—that what is due or necessary is claimed by that which is naturally first from that which is naturally subsequent.

Now the necessity that arises from that which is subsequent in being, and yet is first by nature, is not absolute but conditional necessity (namely, if this must be done, then that must precede). Accordingly, with regard to this necessity, a debt is found in the production of creatures in three ways. First, so that the conditional debt is on the part of the whole universe of things in relation to each part of it that is necessary for the perfection of the universe. For if God willed such a universe to be made, it was due that he should make the sun, moon, and such things, without which the universe cannot be. Second, so that the conditional debt be in one creature in relation to another. For instance, if God willed the existence of plants and animals, it was due that he should make the heavenly bodies, by which those things are preserved, and if he willed the existence of man, he had to make plants and animals and the like, which man needs for perfect existence, although God made both these and other things of his mere will. Third, so that the conditional debt be in each creature in relation to its parts, properties, and accidents, on which the creature depends either for its being, or for some one of its perfections. Thus, given that God willed to make man, it was due, on this supposition, that he should unite in him soul and body, and furnish him with senses and other like aids, both within and without. In all of which, if we consider the matter rightly, God is said to be a debtor not to the creature, but to the fulfilment of his purpose.

There is also in the universe another kind of necessity by which a thing is said to be necessary absolutely. This necessity depends on causes which precede in being: for instance, on essential principles, and on efficient or moving causes. But this kind of necessity cannot find place in the first creation of things as regards efficient causes. For there God alone was the efficient cause, since to create belongs to him alone, as we have proved above.¹ But in creating, he works not by a necessity of his nature, but by his will, as we have shown above.² And those things which are done by the will cannot be necessitated except only by the supposition of the end, on account of which supposition it is due to the end that those things should be by which the end is obtained.

On the other hand, with regard to formal and material causes, nothing hinders us from finding absolute necessity even in the first creation of things. For from the very fact that certain bodies were composed of the elements, it was necessary for them to be hot or cold, and from the very fact that a surface was drawn in the shape of a triangle, it was necessary that it should have three angles equal to two right angles. Now this necessity results from the relation of an effect to its material or formal cause. Therefore, on this account God cannot be said to be a debtor, but rather the debt of necessity falls on the creature. But in the propagation of things, where the creature is already an efficient cause, an absolute necessity can arise from the created efficient cause: thus the lower bodies are necessarily influenced by the movement of the sun.

Accordingly, from the aforesaid kinds of debt, natural justice is found in things both as regards the creation of things, and as regards their propagation. Therefore, God is said to have produced and to govern all things justly and reasonably.

Therefore, by what we have said we remove a twofold error, namely, of those who, setting limits to the divine power, said that God cannot make except what he makes, because he is bound so to make,¹ and of those who assert that all things result from his simple will, without any other reason either to be sought in things, or to be assigned.²

How there can be absolute necessity in created things

Now though all things depend on God’s will as their first cause—which is not necessitated in operating except by the supposition of his purpose—nevertheless absolute necessity is not therefore excluded from things, so that we are obliged to assert that all things are contingent. Someone might think to be the case, for the reason that they have arisen from their cause not of absolute necessity, since in things a contingent effect tends to be one that does not necessarily result from a cause. For there are some created things which it is simply and absolutely necessary must be.

For it is simply and absolutely necessary that those things be in which there is no possibility of not being. Now some things are so brought by God into being that there is in their nature a potency to non-being. This happens through their matter being in potency to another form. Therefore, those things in which there is either no matter, or if there is, it does not have the possibility of receiving another form, do not have a potency to non-being. Hence it is simply and absolutely necessary for them to be.

If, however, it be said that things which are from nothing tend to nothing, so far as they are concerned, and that in consequence there is in all creatures a potency to non-being, it is clear that this does not follow. For created things are said to tend to nothing in the same sense as they are from nothing, and this is not otherwise than according to the power of the agent. Therefore, in created things there is not a potency to non-being, but there is in the Creator the power to give them being or to cease pouring forth being into them, since he works in producing things not by a necessity of his nature, but by his will, as we have proved.¹

Again. Since created things come into being through the divine will, it follows that they are such as God willed them to be. Now the fact that God is said to have brought things into being by his will, and not of necessity, does not exclude his having willed certain things to be necessary, and others contingent, so that there may be an ordinate diversity in things. Nothing, therefore, prevents certain things produced by the divine will being necessary.

Further. It belongs to God’s perfection that he bestowed his likeness on created things, except as regards those things with which created being is incompatible, since it belongs to a perfect agent to produce its like as far as possible. Now to be simply necessary is not incompatible with the notion of created being, for nothing prevents a thing being necessary which nevertheless has a cause of its necessity (for instance, the conclusions of demonstrations). Therefore, nothing prevents a certain thing being so produced by God that it is nevertheless simply necessary for it to be. In fact, this is a proof of the divine perfection.

Moreover. The further distant a thing is from that which is being of itself—namely God—the nearer is it to non-being. Therefore, the nearer a thing is to God, the further is it removed from non-being. Now things that already exist are near to non-being through having a potency to non-being. Consequently, those things which are nearest to God (and for that reason most remote from non-being) must be such that there is no potency to non-being in them, so that the order in things be complete, and the like are necessary absolutely. Therefore, some created things have being necessarily.

Accordingly, it must be observed that if the universe of created beings be considered as coming from their first principle, we find that they depend on the will, not on a necessity of their principle, except on a necessity of supposition, as already stated (ch. 23; Bk. 1, ch. 83). If, however, they be considered in relation to their proximate principles, they are found to have absolute necessity. For nothing prevents certain principles being produced not of necessity, and yet, these being supposed, a certain effect follows of necessity: thus the death of this animal has absolute necessity from the very fact that it is composed of contraries, although it was not absolutely necessary for it to be composed of contraries. In like manner, it was voluntary that such natures were produced by God, and yet, once they are so constituted, something results or happens that has absolute necessity.

In created things, however, necessity is to be taken in various ways in relation to various causes. For, since a thing cannot be without its essential principles, which are matter and form, that which belongs to a thing by reason of its essential principles must have absolute necessity in all things.

Now from these principles, insofar as they are principles of being, a threefold absolute necessity is found in things. First, in relation to the being of the thing of which they are the principles.

And since matter, as regards what it is, is being in potency, and since what can be can also not be, certain things are necessarily corruptible in relation to their matter—such as an animal (through being composed of contraries) and fire (through its matter being susceptive of contraries).

But form, as regards what it is, is act, and by it things exist actually. Therefore, necessity results from it in some things. This happens either because those things are forms without matter—and thus there is no potency to non-being in them, but by their forms they are always in the act of being, as in the case of separate substances—or because their forms are so perfect as to equal the whole potency of their matter; hence there remains no potency to another form (nor, in consequence, to non-being, as in the case of heavenly bodies). But in those things where the form does not fulfill the whole potency of matter, there still remains a potency to another form. Therefore, there is not necessity of being in them, but the act of being in them is the result of form overcoming matter, as in the case of the elements and things composed of them. Now, the form of an element does not reach matter in its whole potency, for matter does not receive the form of one element except by being subjected to the one of two contraries. In contrast, the form of a mixed body reaches matter as disposed by a determinate mode of mixture. Now there must be one same subject of contraries, and of all intermediaries resulting from the mixture of the extremes. Thus it is evident that all things which either have contraries, or are composed of contraries, are corruptible. And things which are not so are everlasting, unless they are corrupted accidentally, like forms which are not subsistent, and have being because they are in matter.

In another way, there is absolute necessity in things from their essential principles, by relation to the parts of their matter or form, if it happens that in certain things these principles are not simple. For, since the proper matter of man is a mixed body, with a certain temperament and endowed with organs, it is absolutely necessary that a man should have in himself each of the elements, humors, and principal organs. Likewise, if man is a rational mortal animal, and this is the nature or form of a man, it is necessary for him to be both animal and rational.

Third, there is absolute necessity in things through the relations of their essential principles to the properties consequent upon their matter or form: thus it is necessary that a saw be hard, since it is of iron, and that a man be capable of learning.

But necessity of the agent may regard either the action itself, or the consequent effect. The former kind of necessity is like the necessity of an accident which it owes to the essential principles. For just as other accidents result from the necessity of essential principles, so does action from the necessity of the form whereby the agent actually is, since it acts so far as it is actual. Yet this happens differently in the action which remains in the agent (such as to understand and to will), and in the action which passes into something else (such as to heat).

For in the former kind of action, the form by which the agent becomes actual causes necessity in the action itself, since for its being nothing extrinsic is required as term of the action. For when the sense is made actual by the sensible species, it is necessary for it to perceive, and in like manner when the intellect is made actual by the intelligible species. But in the second kind of action, necessity of action results from the form as regards the power to act: for if fire is hot, it is necessary that it have the power to heat, although it is not necessary that it heat, since it may be hindered by something extrinsic. Nor does it affect the point at issue whether one agent be sufficient alone for the action by its form, or whether it be necessary to have an assemblage of many agents in order to do the one action (for instance, many men to row a boat): all are as one agent, who is made actual by their being united together in one action.

The necessity which results from an efficient or moving cause in the effect or thing moved depends not only on the agent, but also on a condition of the thing moved and of the recipient of the agent’s action, which recipient either is in potency in no way to receive the effect of such an action—as wool to be made into a saw—or else its potency is hindered by contrary agents, or by contrary dispositions inherent to the movable, or by contrary forms, offering an obstacle that is stronger than the power of the agent in acting—thus iron is not melted by a feeble heat.

Hence, in order that the effect follow, there must be in the patient potency to receive, and in the agent conquest of the patient, so that it be able to transform it to a contrary disposition. And if the effect, resulting in the patient through its conquest by the agent, be contrary to the natural disposition of the patient, there will be necessity of violence, as when a stone is thrown upwards. But if it be not contrary to the natural disposition of the subject, there will be necessity not of violence, but of the natural order, as in the movement of the heavens, which results from an extrinsic active principle, and nevertheless is not contrary to the natural disposition of the movable subject; hence it is not a violent but a natural movement. It is the same in the alteration of lower bodies by the heavenly bodies: for there is a natural inclination in the lower bodies to receive the influence of the higher bodies. It is also thus in the generation of the elements, since the form to be introduced by generation is not contrary to prime matter, which is the subject of generation, although it is contrary to the form to be cast aside, because matter under a contrary form is not the subject of generation.

Accordingly, it is clear from what we have said that the necessity resulting from an efficient cause depends, in some things, on the disposition of the agent alone, but in others on the disposition of both agent and patient. If, then, this disposition, by reason of which the effect follows of necessity, be absolutely necessary in both agent and patient, there will be absolute necessity in the efficient cause, as in those things which act necessarily and always. On the other hand, if it is not absolutely necessary but may be removed, no necessity will result from the efficient cause except on the supposition that both have the disposition required for action—as, for instance, in those things which are sometimes hindered in their operation either through defective power, or through the violence of a contrary. Therefore, they do not act always and necessarily, but in the majority of cases.

From a final cause there results necessity in things in two ways. In one way, insofar as it is first in the intention of the agent. In this respect, necessity results from the end in the same way as from the agent, since the agent acts insofar as it intends the end, both in natural and in voluntary actions. For in natural things, the intention of the end belongs to the agent according to the latter’s form, by which the end is becoming to it. Hence the natural thing must tend to the end according to the virtue of its form, as a heavy body tends towards the center according to the measure of its gravity. And in voluntary matters, the will inclines to act for the sake of an end insofar as it intends that end: although it is not always inclined to do this or that, which are on account of the end, as much as it desires the end, when the end can be obtained not by this or that alone, but in several ways. In another way, necessity results from the end according as this is posterior in being. This is not absolute but conditional necessity: thus we say that it will be necessary for a saw to be made of iron, if it is to do the work of a saw.

That it is not necessary for creatures to have been always

It remains for us to prove from the foregoing that it is not necessary for created things to have been from eternity.

For if it be necessary for the universe of creatures, or any particular creature whatsoever, to be, it must have this necessity either of itself or from another. But it cannot have it of itself. For it was proved above¹ that every being must be from the first being. Now that which has being not from itself cannot possibly have necessity of being from itself, since what must necessarily be cannot possibly not be. Consequently, that which of itself has necessary being, has of itself the impossibility of not being; and therefore it follows that it is not a non-being; and thus that it is a being.

If, however, this necessity of a creature is from something else, it must be from an extrinsic cause, because whatever we may take intrinsic to the creature has being from another. Now an extrinsic cause is either efficient or final. From the efficient cause, however, it follows that the effect necessarily exists when it is necessary for the agent to act, for it is through the agent’s action that the effect depends on the efficient cause. Accordingly, if it is not necessary for the agent to act in order that the effect be produced, neither is it absolutely necessary for the effect to be. Now God does not act of necessity in producing creatures, as we have proved above.¹ Therefore, it is not absolutely necessary for the creature to be, as regards necessity dependent on the efficient cause. Likewise, neither is it necessary as regards the necessity that depends on the final cause. For things directed to an end do not derive necessity from the end, except insofar as without them the end either cannot be—as preservation of life without food—or cannot be so well—as a journey without a horse. Now the end of God’s will, from which things came into being, can be nothing else but his goodness, as we proved in the first book.² And this does not depend on creatures, neither as to its being—since it is essentially necessary being—nor as to well-being—since it is by itself good simply. All of these were proved above.³ Therefore, it is not absolutely necessary for the creature to be, and consequently neither is it necessary to suppose that the creature has been always.

Again. That which proceeds from a will is not absolutely necessary, except perhaps when it is necessary for the will to will it. Now God, as proved above¹ brought things into being not by a necessity of his nature, but by his will: nor does he necessarily will creatures to be, as we proved in the first book.² Therefore, it is not absolutely necessary for the creature to be, and therefore neither is it necessary that it should have been always.

Moreover. It has been proved above¹ that God does not act by an action that is outside him, as though it went out from him and terminated in a creature, like heating which goes out from fire and terminates in wood. But his will is his action, and things are in the way in which God wills them to be. Now it is not necessary that God will the creature always to have been, since neither is it necessary that God will a thing to be at all, as we proved in the first book.² Therefore, it is not necessary that creatures should have been always.

Again. A thing does not proceed necessarily from a voluntary agent except by reason of something due. But God does not produce the creature by reason of any debt, if we consider the production of all creatures absolutely, as we have shown above.¹ Therefore, God does not necessarily produce the creature. Neither, therefore, is it necessary, because God is eternal, that he should have produced the creature from eternity.

Arguments of those who wish to prove the eternity of the world from God’s side of the question

Since, however, many have held that the world has been always and of necessity, and have endeavored to prove this, it remains for us to give their arguments, so as to show that they do not necessarily prove the eternity of the world.¹ In the first place, we shall set forth the arguments that are taken from God’s side; second, those which are taken from the side of creatures;² third, those which are taken from the manner of their making, on account of which they are said to begin to be anew.³

On the part of God the following arguments are produced in order to prove the eternity of the world.

Every agent that does not always act is moved either essentially or accidentally: essentially, as fire which was not always burning begins to burn, either because it is newly lit, or because it is newly transferred so as to be near the fuel; accidentally, as the mover of an animal begins anew to move the animal with some movement made in its regard, either from within—as an animal begins to be moved when it awakes after its digestion is complete—or from without, as when there newly arise actions that lead to the beginning of a new action. Now God is not moved, neither essentially nor accidentally, as we proved in the first book.¹ Therefore, God always acts in the same way. But created things are established in being by his action. Therefore, creatures always have been.

Again. The effect proceeds from the active cause by the latter’s action. But God’s action is eternal: else he would become an actual agent from being an agent in potency, and he would have to be reduced to act by some previous agent, which is impossible. Therefore, the things created by God have been from eternity.

Moreover. Given a sufficient cause, its effect must necessarily be granted. For if, given the cause, it were still unnecessary to grant its effect, it would be therefore possible that, given the cause, the effect would be or not be. Therefore, the sequence of the effect to its cause would only be possible, and what is possible requires something to reduce it to act. Hence it will be necessary to suppose some cause whereby it comes about that the effect is made actual: and thus the first cause was not sufficient. But God is the sufficient cause of creatures being produced, or else he would not be a cause. Rather he would be in potency to a cause, since he would become a cause by the addition of something, which is impossible. Therefore, it would seem necessary, since God is from eternity, that the creature was also from eternity.

Again. A voluntary agent does not delay to carry out his purpose of making a thing, except on account of something expected and not yet present. This latter is either sometimes in the agent himself, as where one awaits perfect capability to do something, or the removal of an obstacle to one’s capability; and sometimes it is outside the agent, as when one awaits the presence of a person in whose presence the action is to be done, or at least when one awaits the presence of a suitable time which has not yet arrived. For if the will be complete, the power immediately follows, unless there be a fault in it: thus at the command of the will, the movement of a limb follows at once, unless there be a fault in the motive power which carries out the movement.

Hence it is clear that when one wills to do a thing and it is not done at once, it must be either that this is owing to a fault in the power, of which fault one awaits the removal, or else the will to do it is not complete. And by the will being complete I mean that it wills to do this thing absolutely and from every point of view, whereas the will is incomplete when one does not will absolutely to do this thing, but on a certain condition that does not yet obtain, or when one does not will it except a present obstacle be removed. Now it is evident that whatever God now wills to be, he has willed from eternity to be, for a new movement of the will cannot accrue to him. Neither could any fault or obstacle affect his power: nor could anything else be awaited for the universal production of creatures, since nothing besides him is uncreated, as we have proved above.¹ Therefore, it is seemingly evident that he produced the creature from eternity.

Again. Things directed to an end take their necessity from the end, especially in those that are done voluntarily. Hence it follows that as long as there is no change in the end, things directed to the end suffer no change or are produced invariably, unless there arise some new relation between them and the end. Now the end of creatures, which proceed from the divine will, is the divine goodness, which alone can be the end of the divine will.¹ Therefore, since the divine goodness is unchangeable both in itself and in relation to the divine will throughout all eternity, it would seem that creatures are brought into being by the divine will in the same way through the whole of eternity: for it cannot be said that any new relation to the end accrued to them, if it be supposed that they were utterly nonexistent before a particular time from which they are supposed to have begun their existence.

Further. Since the divine goodness is most perfect, when we say that all things came from God on account of his goodness, the sense is not that anything accrued to him from creatures, but that it belongs to goodness to communicate itself to others as far as possible, and it is by doing so that goodness makes itself known. Now since all things partake of God’s goodness insofar as they have being, the more lasting they are, the more they participate in the goodness of God. Hence the everlasting being of a species is called a divine being.¹ But the divine goodness is infinite. Consequently, it belongs to it to communicate itself in an infinite manner, and not only at a particular time. Therefore, it would seem to belong to the divine goodness that some creatures should have existed from eternity.

Accordingly, these are the arguments taken from God’s side, which would seem to show that creatures have been always.

Arguments of those who would prove the eternity of the world from the point of view of creatures

There are also other arguments, taken from the point of view of creatures, that would seem to prove the same conclusion.

For things which have no potency to non-being cannot possibly not be. Now there are some creatures in which there is no potency to non-being. For there cannot be potency to non-being except in those things which have matter subject to contrariety, since potency to being and to non-being is a potency to privation and form, of which matter is the subject; and privation is always connected with the opposite form, since it is impossible for matter to be without any form at all. But there are certain creatures in which the matter is not subject to contrariety, either because they are entirely devoid of matter, for instance, intellectual substances, as we shall show further on,¹ or because they have no contrary, as heavenly bodies, and this is proved by their movement, which has no contrary. Therefore, it is impossible for certain creatures not to exist, and consequently it is necessary that they exist always.

Again. A thing’s endurance in being is in proportion to its power of being, except accidentally, as in those which are corrupted by violence. But there are certain creatures in which there is a power of being not for any definite time, but forever (for instance, the heavenly bodies and intellectual substances, because they are incorruptible through having no contrary). It follows, then, that it is competent to them to be always. But that which begins to exist, is not always. Therefore, it is not becoming to them that they begin to exist.

Further. Whenever a thing begins to be moved anew, the mover, the moved, or both must be conditioned otherwise now, while the movement is, than before, when there was no movement. For there is a certain habitude or relation in the mover to the thing moved insofar as it moves actually; and the new relation does not begin without a change either in both or at least in one or other of the extremes. Now that which is conditioned otherwise now and before is moved.¹ Therefore, before the movement that begins anew there must be a previous movement either in the movable or in the mover. It follows, in consequence, that every movement is either eternal or has another movement preceding it. Therefore, movement always has been, and so also has the movable. Therefore, there have always been creatures, since God is utterly immovable, as we proved in the first book.²

Again. If time is everlasting, movement must be everlasting, since it is the reckoning of movement.¹ Consequently, movables must be everlasting, since movement is the act of a movable.² Now time must be perpetual. For time is inconceivable without a now, even as a line is inconceivable without a point. But “now” is always the end of the past and the beginning of the future, for this is the definition of the now.³ Therefore, every given now has time preceding it and following it, and consequently no now can be either first or last. It follows, therefore, that movables, which are created substances, are from eternity.

Again. One must either affirm or deny. If, therefore, by denying a thing we suppose its existence, that thing must be always. Now time is a thing of this kind. For if time was not always, we can conceive it as not being previously to being. In like manner, if it will not be always, its non-being must follow its being. Now there can be no before and after in duration unless there be time, since the reckoning of before and after is time.¹ Consequently, time must have been before it began to be, and will be after it has ceased to be: and therefore time is eternal. But time is an accident, and an accident cannot be without a subject. And its subject is not God, who is above time, since he is utterly immovable, as we proved in the first book.² Therefore, it follows that some created substance is eternal.

Moreover. Many propositions are such that to deny them is to affirm them: for instance, anyone who denies that truth exists, supposes the existence of truth, for he supposes that the denial which he utters is true. It is the same with one who denies the principle that contradictories are not simultaneous, since by denying this, he asserts that the negative which he utters is true, and that the opposite affirmative is false, and thus that both are not true about the same thing. Accordingly if, as we have proved,¹ a thing which through being denied has to be admitted, must be always, it follows that the aforesaid propositions, and all that result from them, are everlasting. But such propositions are not God. Therefore, something beside God must be eternal.

These, then, and similar arguments may be taken from the standpoint of creatures to prove that creatures have been always.

Arguments to prove the eternity of the world from the point of view of the making

Again, other arguments may be taken from the point of view of the making, in order to prove the same conclusion.

For what is asserted by all in common cannot possibly be entirely false, because a false opinion is a weakness of the understanding, even as a false judgment about its proper sensible results from a weakness of the sense. Now defects are accidental, since they are beside the intention of nature. And what is accidental cannot be always and in everything: for instance, the judgment given by all tastes about flavors cannot be false. Consequently, the judgment given by all about a truth cannot be erroneous. Now it is the common opinion of all philosophers that from nothing, naught is made.¹

Therefore, this must be true. Hence if a thing is made, it must be made from something, and if this also is made, it must also be made from something. But this cannot go on indefinitely, for then no generation would be completed, since it is not possible to go through an infinite number of things. Therefore, we must come to some first thing that was not made. Now everything that has not always been must have been made. Therefore, the thing from which all things were first made must be eternal. But this is not God, since he cannot be the matter of a thing, as we proved in the first book.¹ Therefore, it follows that something beside God is eternal, namely, prime matter.

Moreover. If a thing is not in the same state now and before, it must be changed in some way, for to be moved is not to be in the same state now as before.¹ Now everything that begins to be anew is not in the same state now as before. Therefore, this must result from some movement or change. But every movement or change is in a subject, for it is the act of a movable.² Now, since movement precedes that which is made by movement, for movement terminates in it, it follows that there preexists a movable subject before anything made. And since this cannot go on indefinitely, we must necessarily come to some first subject that begins not anew but always has been.

Again. Whatever begins to be anew, it was possible, before it was, that it would be. For if not, it was impossible for it to be and necessary for it not to be, so it would always have been a non-being, and it never would have begun to be. Now that for which it is possible to be is a subject potentially a being.¹ Therefore, before everything that begins to be anew, there must preexist a subject which is a potential being. And since this cannot go on indefinitely, we must suppose some first subject which did not begin to be anew.

Again. No permanent substance is while it is being made, for it is made in order that it may be; therefore, it would not have to be made if it were already. But while it is being made, there must be something that is the subject of the making, since a making, since it is an accident, cannot be without a subject. Therefore, whatever is made has a preexisting subject. And since this cannot go on indefinitely, it follows that the first subject was not made, but is eternal. Hence it also follows that something beside God is eternal, because he cannot be the subject of making or movement.

Accordingly, these are the arguments by which some people say that things created have necessarily been always, clinging to them as though they were demonstrations In this, they contradict the Catholic faith, which affirms that nothing beside God has always been, and that all things have begun to be, save the one eternal God.

Solution of the foregoing arguments, and first of those taken from the standpoint of God

We must, accordingly, show that the foregoing reasons do not necessarily conclude, starting with those that are produced on the part of the agent.¹

For it does not follow that God is moved either essentially or accidentally if his effect begin to be anew, as the first argument argued. For newness of effect may indicate change of the agent insofar as it proves newness of action, for it is impossible for a new action to be in the agent unless the latter be in some way moved (at least from inaction to action). But newness of effect does not prove newness of action in God, since his action is his essence, as we have proved above.¹ Neither, therefore, can newness of effect argue change in God the agent.

And yet it does not follow, if the action of the first agent is eternal, that his effect is eternal, as the second argument inferred. For it has been shown above¹ that in producing things God acts voluntarily. Not, however, as though there were an intermediate action of his—as in us the action of the motive power intervenes between the act of the will and the effect, as we have proved in a foregoing chapter²—but his act of understanding and willing must be his act of making. Now the effect follows from the intellect and the will according to the determination of the intellect and the command of the will. And just as every other condition of the thing made is determined by the intellect, so is time appointed to it: for art determines not only that this thing is to be such and such, but that it is to be at this particular time, even as a physician determines that a draught is to be taken at such and such a time. Therefore, if his willing were essentially efficacious for producing the effect, the effect would follow anew from his former will without any new action on his part. Therefore, nothing prevents our saying that God’s action was from eternity while his effect was not from eternity, but from the time when he appointed it from eternity.

Hence it is also clear that, although God is the sufficient cause of bringing things into being, it is not necessary to suppose that because he is eternal, his effect is eternal, as the third argument contended. For if we suppose a sufficient cause, we suppose its effect, but not an effect outside the cause: for this would be through insufficiency of the cause (for instance, as if a hot thing failed to give heat). Now the proper effect of the will is for that thing to be which the will wills: and if something else were to be than what the will wills, this would be an effect that is not proper to the cause, but foreign to it. But just as the will, as we have said, wills this thing to be such and such, so does it will it to be at such and such a time. Therefore, for the will to be a sufficient cause, it is not necessary for the effect to be when the will is, but when the will has appointed the effect to be. On the other hand, it is different with things which proceed from a cause acting naturally, because the action of nature is according as nature is; therefore, the effect must necessarily follow if the cause exists. Now, the will acts not according to the mode of its being, but according to the mode of its purpose. And consequently, just as the effect of a natural agent follows the being of the agent, so the effect of a voluntary agent follows the mode of his purpose.

From the foregoing it is again clear that the effect of the divine will is not delayed, although it was not always, since it was always willed, as the fourth reason argued. This is so because the object of the divine will is not only the existence of the effect, but also the time of its existence. Therefore, the thing willed (namely, that a creature should exist at such and such a time) is not delayed, because the creature began to exist at the time appointed by God from eternity.

Nor can we conceive a diversity of parts of any duration before the beginning of the whole creature, as was supposed in the fifth argument. For nothingness has neither measure nor duration. And the duration of God, which is eternity, has no parts, but is utterly simple, having no before and after, since God is immovable, as stated in the first book.¹ Therefore, there is no comparison between the beginning of the whole creature and any various signate parts of an already existing measure, to which parts the beginning of creatures can be related in a like or unlike manner, so that there need be a reason in the agent why he should have produced the creature at this particular point of that duration, and not at some particular or subsequent point. Such a reason would be necessary if there were some duration divisible into parts beside the whole creature produced, as happens in particular agents, who produce their effect in time but do not produce time itself. But God brought into being both the creature and time together. Hence in this matter we do not have to consider the reason he produced them now and not before, but only why not always.

This may be made clear by a comparison with place. For particular bodies are produced not only at a determined time, but also in a determined place; and since time and place by which they are contained are extraneous to them, there must be a reason why they are produced in this place and time rather than in another: whereas in the whole heaven, outside which there is no place, and together with which the entire place of all things is produced, we do not have to consider the reason why it is produced here and not there. Through thinking that this reason ought to be a matter of consideration, some have fallen into error, so as to place the infinite in bodies. In like manner, in the production of the entire creature, outside which there is no time, and together with which time is produced simultaneously, we do not have to consider the reason why it was produced now and not before (so that we be led to grant the infinity of time), but only why it was not always produced, or why after non-being, or so as to imply a beginning.

For the purpose of inquiring into this question, the sixth argument was adduced on the part of the end, which alone can bring about necessity in those things which are done voluntarily. Now the end of God’s will can only be his goodness. And he does not act in order to bring this end into being, as a craftsman works in order to produce his handiwork, since his goodness is eternal and unchangeable, so that nothing can accrue to it. Nor could it be said that God works for his betterment. Nor again does he act in order to obtain this end for himself, as a king fights in order to obtain possession of a city: for he is his own goodness. It remains, therefore, that he acts for an end by producing an effect, so that it participate his end. Accordingly, in thus producing an effect on account of an end, the uniform relation of the end to the agent is not to be taken as a reason for his work being eternal. Rather, we should consider the relation of the end to the effect which is made on account of the end, so that the effect be produced in such a way as to be most fittingly directed to the end. Consequently, we cannot conclude that the effect is eternal from the fact that the end is uniformly related to the agent.

Nor is it necessary that the divine effect should have been always, because thus it is more fittingly directed to the end, as the seventh argument seemed to infer; however, it is more fittingly directed to the end by the fact that it was not always. For every agent that produces an effect in participation of his own form intends to produce his likeness in it. Therefore, it was becoming to God’s will to produce the creature in participation of his goodness, so that it might reflect the divine goodness by its likeness. But this reflection cannot be by way of equality, as a univocal effect reflects its cause—so that it be necessary for eternal effects to be produced by the divine goodness—but it is after the manner in which the transcendent is reflected by that which is transcended. Now the transcendence of the divine goodness over the creature is especially manifested by the fact that creatures have not been always. For by that, it is manifest that all else beside him has him as the author of its being, and that his power is not constrained to produce these effects as nature is to natural effects, and consequently that he is a voluntary and intelligent agent. Some have affirmed the opposite through maintaining the eternity of creatures.

Accordingly, there is nothing on the part of the agent to oblige us to hold the eternity of creatures.

Solution of the arguments produced on the part of the things made

In like manner, neither is there anything on the part of creatures to induce us to assert their eternity.

For the necessity of being that we find in creatures, from which the first argument is taken, is a necessity of order, as was shown above:¹ and a necessity of order does not compel the subject of a like necessity to have been always, as we proved above.² For although the substance of heaven has a potency to being through being devoid of potency to non-being, yet this necessity follows its substance. Therefore, once its substance is brought into being, this necessity involves the impossibility of not being, but it does not make it impossible for the heaven not to be from the point of view where we consider the production of its very substance.

Likewise, the power to be always, from which the second argument proceeded, presupposes the production of the substance. Hence where the production of the heaven’s substance is in question, this power cannot be a sufficient argument for that substance’s eternity.

Again, the argument adduced in sequence does not compel us to admit the eternity of movement. For it is clear¹ that without any change in God the agent, he can do something new that is not eternal. Now if it is possible him to do something anew, it is evident that he can also move something anew, for newness of movement follows on the ordinance of the eternal will to the effect that movement be not always.

Likewise, the intention which natural agents have of perpetuating the species, which was the starting point of the fourth argument, presupposes that natural agents are already in being. Therefore, this argument has no place save in natural things already brought into being—but not when it is a question of the (first) production of things. The question as to whether it is necessary to admit that generation will go on forever will be discussed in the sequel.¹

Also, the fifth argument, taken from time, supposes rather than proves the eternity of movement. For, since before and after and continuity of time are consequent upon before and after and continuity of movement (according to the teaching of Aristotle),¹ it is clear that the same instant is the beginning of the future, and the end of the past, because in movement there is something assignable that is the beginning and end of the various parts of movement. Therefore, it will not be necessary for each instant to be thus, unless every assignable instant that we conceive in time be between before and after in movement, and this is to suppose that movement is eternal. But he who supposes that movement is not eternal can say that the first instant of time is the beginning of the future, and the end of no past. Nor is it incompatible with the succession of time if we place in it a “now” that is a beginning and not an end, because a line in which we place a point that is a beginning and not an end is stationary and not transitory. For even in a particular movement, which also is not stationary but transitory, it is possible to designate something as only a beginning, and not an end, of movement: for otherwise all movement would be perpetual, which is impossible.

That we suppose the non-being of time to precede its being, if time began, does not compel us to say that time is, if we suppose that it is not, as the sixth argument inferred. For the “before” that we speak of as being before time does not imply any part of time in reality, but only in our imagination. For when we say that time has being after non-being, we mean that there was no part of time before this signate now: thus, when we say that there is nothing above the heaven, we do not mean that there is a place outside the heaven which can be said to be above in relation to the heaven, but that there is no place above it. In either case, the imagination can apply a measure to the already existing thing, and just as this measure is no reason for admitting infinite quantity in a body, as stated in Physics 3,¹ so neither is it a reason for supposing that time is eternal.

The truth of propositions which one has to grant even if one denies them, and from which the seventh argument proceeded, has the necessity of that relation which is between predicate and subject. Therefore, it does not compel a thing to be always, except perhaps (as understood) by the divine intellect in which all truth is rooted, as we showed in the first book.¹

Hence it is clear that the arguments taken from creatures do not compel one to assert the eternity of the world.

Solution of the arguments taken from the making of things

It remains for us to show that neither does any argument taken from the point of view of the making of things compel us to draw the aforesaid conclusion.¹

The common opinion of the philosophers who asserted that nothing is made from nothing (on which the first argument was based) holds good for that particular making which they had under consideration. For, since all our knowledge begins from the senses which are about singulars, human speculations proceeded from particular to universal considerations. Therefore, those who sought the principle of things considered only the particular makings of beings, and inquired in what manner this particular fire or this particular stone was made.

At first, considering the making of things more from an outward point of view than they should have, they stated that a thing is made only in respect of certain accidental dispositions, such as rarity, density, and so forth. They said, in consequence, that to be made was nothing else than to be altered, for the reason that they understood everything to be made from an actual being. Later on, they considered the making of things more inwardly and made a step forward to the making of things in regard to their substance, for they asserted that a thing does not need to be made from an actual being except accidentally, and that it is made in itself from a being in potency.

But this making, which is of a being from any being whatsoever, is the making of a particular being, which is made insofar as it is this being (for instance, a man or a fire), but not insofar as it is considered universally: for there was previously a being which is transformed into this being. Entering still more deeply into the origin of things, they considered at last the procession of all created being from one first cause, as appears from the arguments given above¹ which prove this.

In this procession of all being from God, it is not possible for anything to be made from something already existing, since it would not be the making of all created being. The early natural philosophers had no conception of such a making, for it was their common opinion that nothing is made from nothing. Or if any of them conceived the idea, they did not consider that the name of “making” was applicable to it, since the word “making” implies movement or change, whereas in this origin of all being from one first being, the transformation of one being into another is inconceivable, as we have proved.¹ Because of this, neither does it belong to the natural philosophers to consider this same origin of things, but to the metaphysician, who considers universal being and things that are devoid of movement. We, however, transfer the name “making” by a kind of metaphor even to that origin, so that we say that anything is made if its essence or nature originates from something else.

Therefore, it is clear that neither does the second argument follow, which was taken from the nature of movement. For creation cannot be described as a change save metaphorically, insofar as the created thing is considered to have being after non-being, in which way one thing is said to be made out of another—even in those things where the one is not changed into the other—only because one succeeds the other, as day out of night. Nor does the nature of movement that is brought into the argument justify the conclusion, since what in no way exists is not in any particular state, so that it follows that when it begins to exist, it is in a different state now and before.

Hence again it is evident that there is no need for a passive potency to precede the existence of all created being, as the third argument inferred. For this is necessary in those things which take their origin of being from movement, since movement is the act of a potential being.¹ But before a created thing was, it was possible for it to be through the power of the agent, by which power also it began to be. Or it was possible on account of the relation of the terms, in which no incompatibility is found: which kind of possibility is said to be in respect of no potency, as the Philosopher says in Metaphysics 5.² For this predicate “being” is not incompatible with this subject “world” or “man,” as “measurable” is incompatible with “diameter.” And thus it follows that it is not impossible for it to be, and consequently that before it was, it was possible for it to be, apart from all potency. But in those things which are made by movement, it is necessary that they be previously possible in respect of a passive potency, and it is with regard to these that the Philosopher employs this argument in Metaphysics 7.³

From this it is also clear that neither is the fourth argument conclusive for the purpose. For in things made by movement, to be made and to be are not simultaneous, because succession is found in their making. In things that are not made by movement, however, their making is not before their being.

It is, therefore, evident that nothing prevents our asserting that the world has not been always, and this is affirmed by the Catholic faith: in the beginning God created the heavens and the earth (Gen 1:1); and it is said of God: before anything was made, from the beginning (Prov 8:22).

Arguments by which some endeavor to prove that the world is not eternal

Now there are some arguments brought forward by certain people to prove that the world was not always: they are taken from the following.

For it has been proved that God is the cause of all things. But a cause must precede in duration the things made by its action.

Again. Since all being is created by God, it cannot said to be made from some being, so that it must be made from nothing, and consequently has being after non-being.

Also, because it is not possible to pass by an infinite number of things. Now if the world were always, an infinite number of things would have now been passed by, since what is past, is passed by, and if the world was always, there is an infinite number of days or an infinite number of solar revolutions.

Moreover. It follows that it is possible to go on to infinity in efficient causes if there were always generation. We are bound to admit this latter if the world was always, for the son’s cause is his father, and another man is the latter’s father, and so on into infinity.

Again. It will follow that there is an infinite number of things, namely, the immortal souls of an infinite number of men.

Now since these arguments do not conclude of absolute necessity, although they are not devoid of probability, it is enough merely to touch upon them, lest the Catholic faith seem to be founded on empty reasonings, and not, as it is, on the most solid teaching of God. Therefore, it seems right that we should indicate how those arguments are met by those who asserted the eternity of the world.

For the first statement—that an agent necessarily precedes the effect brought about by its operation—is true of those things which act by movement, because the effect is not until the movement is ended, and the agent must necessarily exist even when the movement begins. But in those things which act instantaneously, this is not necessary: thus as soon as the sun reaches the point of the East, it enlightens our hemisphere.

Also, that which is said in the second place is of no avail. For, in order to contradict the statement “something is made from something,” if this is not granted, we must say “something is not made from something,” and not “something is made from nothing,” except in the sense of the former. Hence we cannot conclude that it is made after not being.

Again, the third argument is not cogent. For, though the infinite in act be impossible, it is not impossible in succession, since any given infinite taken in this sense is finite. Hence each of the preceding revolutions could be passed by, since it was finite. But in all of them together, if the world had been always, there would be no first revolution. Therefore, there would be no passing through them, because this always requires two extremes.

Again, the fourth argument put forward is weak. For nothing hinders the infinite receiving an addition on the side on which it is finite. Now supposing time to be eternal, it follows that it is infinite anteriorly but finite posteriorly, since the present is the term of the past.

Nor is the argument cogent which is given in the fifth place. For, according to philosophers, it is impossible to have an infinite number of active causes which act together simultaneously, because the effect would have to depend on an infinite number of simultaneous actions. Such are causes that are essentially infinite, because their infinity is required for their effect. On the other hand, in causes that do not act simultaneously this is not impossible, according to those who assert that generation has always been. And this infinity is accidental to the causes, for it is accidental to the father of Socrates that he is another man’s son or not. But it is not accidental to the stick that it be moved by the hand insofar as it moves the stone, since it moves insofar as it is moved.

The objection taken from souls is more difficult. And yet the argument is not of much use, since it takes many things for granted.¹ For some of those who maintained the eternity of the world asserted that human souls do not survive the body. Some said that of all souls there survives only the separate intellect, or the active intellect according to some, or even the passive intellect according to others. Some have held a kind of rotation in souls, saying that the same souls after several centuries return to bodies. And some do not consider it incongruous that there should be things actually infinite in those which have no order.

Nevertheless, one may proceed to prove this more efficiently from the end of the divine will, as we have indicated above.¹ For the end of God’s will in the production of things is his goodness as manifested in his effects. Now God’s might and goodness are especially made manifest in that things other than himself were not always. For the fact that they have not always been clearly shows that other things beside himself have their being from him. It also shows that he does not act by a necessity of his nature, and that his power is infinite in acting. Therefore, it was most becoming to the goodness of God that he should give his creatures a beginning of their duration.

From what has been said we are able to avoid the various errors of the pagan philosophers. Of these, some asserted the eternity of the world. Others asserted that the matter of the world is eternal, out of which at a certain time the world began to be formed either by chance, by some intellect, or by love and strife. For all these suppose something eternal beside God, which is incompatible with the Catholic faith.

The distinction of things

That the distinction of things is not from chance

Having disposed of those matters which relate to the production of things, it remains for us to treat of those which call for our consideration as regards the distinction of things.¹ Of these the first that we have to prove is that the distinction of things is not from chance.

For chance occurs only in those things which can possibly be otherwise, since we do not ascribe to chance those that are necessarily and always. Now it was shown above¹ that certain things have been created in whose nature there is no possibility of not being, such as immaterial substances and those which are not composed of contraries. Therefore, it is impossible that their substances be from chance. But it is by their substances that they are mutually distinct. Therefore, their distinction is not from chance.

Moreover. Since chance is only in those things that are possibly otherwise, and since the principle of this possibility is matter and not their form (which in fact determines the possibility of matter to one), it follows that those things which are distinct by their forms are not distinct by chance, but perhaps those things are whose distinction is from matter. But the distinction of species is from the form, and the distinction of singulars in the same species is from matter. Therefore, the specific distinction of things cannot be from chance, but perhaps chance causes the distinction of certain individuals.

Also. Since matter is the principle and cause of casual things, as we have shown, there may be chance in the making of things produced from matter. But it was proved above¹ that the first production of things into being was not from matter. Therefore, there is no place for chance in them. Yet the first production of things must have included their distinction, since there are many created things which are neither produced from one another, nor from something common, because they do not agree in matter. Therefore, it is impossible for the distinction of things to be from chance.

Again. An essential cause is before an accidental cause. Hence if later things are from a determinate essential cause, it is unfitting to say that the first things are from an undeterminate accidental cause. Now the distinction of things naturally precedes their movements and operations, since determinate movements and operations belong to things determinate and distinct. But movements and operations of things are from essential and determinate causes, since we find that they proceed from their causes in the same way either always or for the most part. Therefore, the distinction of things is also from an essential determinate cause, and not from chance, which is an indeterminate accidental cause.

Moreover. The form of anything that proceeds from an intellectual voluntary agent is intended by the agent. Now the universe of creatures has God as its author, who is an agent by his will and intellect, as proved above.¹ Nor can there be any defect in his power, so that he fail of his intention, since his power is infinite, as was proved above.² It follows, therefore, that the form of the universe is intended and willed by God. Therefore, it is not from chance: for we ascribe to chance those things which are beside the intention of the agent. Now the form of the universe consists in the distinction and order of its parts. Therefore, the distinction of things is not from chance.

Further. That which is good and best in the effect is the end of its production. But the good and the best in the universe consists in the mutual order of its parts, which is impossible without distinction, since by this order the universe is established as one whole, and this is its best. Therefore, the order of the parts of the universe and their distinction is the end of the production of the universe. Therefore, the distinction of things is not from chance.

Sacred Scripture bears witness to this truth, as is clear from Genesis 1, where, after the words: in the beginning God created the heavens and earth (1:1), the text continues: God separated the light from the darkness (1:4), and so with the rest, in order that not only the creation of things, but also their distinction, is shown to be from God and not from chance, but as the good and the best of the universe. Therefore, it is added: God saw everything that he had made, and behold, it was very good (1:31).

By this is excluded the opinion of the ancient natural philosophers, who affirmed that there was only a material cause and no other, from which all things were made by expansion and cohesion.¹ For these had to say that the distinction of things which we observe in the universe resulted not from the intentional ordinance of one, but from the chance movement of matter.

Likewise is excluded the opinion of Democritus and Leucippus,¹ who postulated an infinite number of material principles, namely, indivisible bodies of the same nature, but differing in shape, order, and position, to whose convergence—which must be fortuitous, since they denied the existence of an active cause—they ascribed the diversity among things, on account of the three aforesaid differences of atoms (namely, of shape, order, and position). Therefore, it followed that the distinction of things was by chance: and from what has been said, this is clearly false.

That matter is not the first cause of the distinction of things

Furthermore, it is evident from the foregoing that the distinction of things is not on account of a diversity of matter as its first cause.

For nothing determinate can proceed from matter except by chance, for matter is in potency to many things. If only one of these were to result, this must happen in the minority of cases. And such is what happens by chance, especially if we remove the intention of an agent. Now it was proved¹ that the distinction of things is not from chance. It follows, therefore, that it is not on account of a diversity of matter as its first cause.

Again. Those things which result from the intention of an agent are not on account of matter as their first cause. For an active cause precedes matter in acting, because matter does not become an actual cause except insofar as it is moved by an agent. Therefore, if an effect is consequent upon a disposition of matter and the intention of an agent, it does not result from matter as its first cause. For this reason, we find that those things referable to matter as their first cause are beside the intention of the agent (for instance, monsters and other mischances of nature). But the form results from the intention of the agent. This is proved thus: the agent produces its like according to its form, and if this sometimes fails, it is from chance, on account of a defect in the matter. Therefore, forms do not result from a disposition of matter as their first cause; on the contrary, matters are disposed in such a way that such may be their forms. Now the specific distinction of things is according to their forms. Therefore, the distinction of things is not on account of the diversity of matter as its first cause.

Moreover. The distinction of things cannot result from matter except in those which are made from preexisting matter. Now many things are distinguished from one another which cannot be made from preexisting matter (for instance, the celestial bodies, which have no contrary, as their movement shows). Therefore, the diversity of matter cannot be the first cause of the distinction of things.

Again. Whatever things, having a cause of their being, are distinct from one another have a cause of their distinction, because a thing is made a being according as it is made one, undivided in itself and distinct from others. Now if matter, by its diversity, is the cause of the distinction of things, we must suppose that matters are in themselves distinct. Moreover, it is evident that every matter has being from something else, since it was proved above¹ that everything that is in any way whatsoever is from God. Therefore, something else is the cause of distinction in matters, and consequently the first cause of the distinction of things cannot be a diversity of matter.

Again. Since every intellect acts for the sake of good, it does not produce a better thing for the sake of an inferior thing: and it is the same with nature. Now all things proceed from God, who acts by his intellect, as stated above.¹ Therefore, inferior things proceed from God for the sake of better things, and not vice versa. But form is more noble than matter, since it is its perfection and act. Therefore, he does not produce such and such forms for the sake of such and such matters, but rather he produced such and such matters that there might be such and such forms. Therefore, the specific distinction in things, which is according to their form, is not on account of their matter. On the contrary, matters were created diverse so that they might be suitable for diverse forms.

By this is excluded the opinion of Anaxagoras, who postulated an infinite number of material principles, which at first were mixed together in one confused mass, but which an intellect subsequently separated, thus establishing a distinction among things,¹ as well as the opinions of any who held the distinction of things to be the result of various material principles.

That the distinction of things is not on account of a contrariety of agents

From the above we may also prove that the cause of distinction among things is not a diversity or even a contrariety of agents.

For if the diverse agents who cause the diversity among things are ordered to one another, there must be some cause of this order, since many are not united together save by some one. And thus the principle of this order will be the first and sole cause of the distinction of things. If, on the other hand, these various agents are not ordered to one another, their convergence to the effect of producing the diversity of things will be accidental: therefore, the distinction of things will be by chance—the contrary of which has been proved above.¹

Again. Ordered effects do not proceed from diverse causes having no order, except perhaps accidentally, for diverse things as such do not produce one. Now things mutually distinct are found to have a mutual order, and this is not by chance, since for the most part one is helped by another. Therefore, it is impossible that the distinction among things thus ordered be on account of a diversity of agents without order.

Moreover. Things that have a cause of their distinction cannot be the first cause of the distinction of things. Now, if we take several coordinate agents, they must have a cause of their distinction, because they have a cause of their being, since all beings are from one first being, as was shown above.¹ Now the cause of a thing’s being is the same as the cause of its distinction from others, as we have proved.² Therefore, diversity of agents cannot be the first cause of distinction among things.

Again. If the diversity of things comes of the diversity or contrariety of various agents, this would seem especially to apply, as many maintain, to the contrariety of good and evil, so that all good things proceed from a good principle, and evil things from an evil principle: for good and evil are in every genus. But there cannot be one first principle of all evil things. For, since those things that are through another are reduced to those that are of themselves, it would follow that the first active cause of evils is evil of itself. Now a thing is said to be such “of itself” if it is such by its essence. Therefore, its essence will not be good. But this is impossible. For everything that exists must of necessity be good insofar as it is a being, because everything loves its being and desires it to be preserved (a sign of which is that everything resists its own corruption, and good is what all desire).¹ Therefore, distinction among things cannot proceed from two contrary principles, the one good, and the other evil.

Further. Every agent acts insofar as it is actual. But everything is perfect insofar as it is in act, and everything that is perfect, as such, is said to be good. Therefore, every agent, as such, is good. Therefore if a thing is essentially evil, it cannot be an agent. But if it is the first principle of evils, it must be essentially evil, as we have proved. Therefore, it is impossible that the distinction among things proceed from two principles, good and evil.

Moreover. If every being, as such, is good, it follows that evil, as such, is a non-being. Now, no efficient cause can be assigned to non-being, as such, since every agent acts insofar as it is an actual being, and every agent produces its like. Therefore, no essentially efficient cause can be assigned to evil, as such. Therefore, evils cannot be reduced to one first cause that is of itself the cause of all evils.

Further. That which results beside the intention of the agent, has no essential cause, but happens accidentally (for instance, when a man finds a treasure while digging to plant). Now evil cannot result in an effect except beside the intention of the agent, for every agent intends a good, since the good is what all desire.¹ Therefore, evil does not have an essential cause, but happens accidentally in the effects of causes. Therefore, we cannot assign one first principle to all evils.

Moreover. That which altogether is not is neither good nor evil. Now that which is, insofar as it is, is good, as proved above. Therefore, a thing is evil insofar as it is a non-being. But this is a being with a privation. Therefore, evil as such is a being with a privation, and the evil itself is this very privation. Now privation has no essential efficient cause, since every agent acts inasmuch as it has a form; and thus the essential effect of an agent must be something having that form, because an agent produces its like, except accidentally. It follows, then, that evil has no essential efficient cause, but happens accidentally in the effects of causes which are essentially effective.

Consequently, there is not one essential principle of evil, but the first principle of all things is one first good, in whose effects evil is an accidental consequence.

Hence it is said: I am the Lord, and there is no other. I form light and create darkness, I make peace and create evil; I am the Lord, who do all these things (Isa 45:6–7). And: good things and bad, life and death, poverty and wealth, come from the Lord (Sir 11:14). And: good is the opposite of evil . . . so the sinner is the opposite of the godly. Look upon all the works of the Most High; they likewise are in pairs, one the opposite of the other (Sir 33:14–15).

God is said to make or create evils, insofar as he creates things that are good in themselves, and yet hurtful to others: for instance, the wolf, although in his species he is a good of nature, is nevertheless evil to the sheep; and likewise fire to water, inasmuch as it is corruptive of it. In like manner, he causes in men those evils called “punishments.” Hence it is said: does evil befall a city unless the Lord has done it? (Amos 3:6). In this sense Gregory says: even evils, which have no natural subsistence of their own, are created by the Lord. But he is said to ‘create’ evils when he employs creatures that are good in themselves to punish us who do evil.¹

By this is excluded the error of those who asserted contrary first principles. This error began with Empedocles, for he held that there are two first active principles, love and strife, of which he asserted that love is the cause of generation, and strife the cause of corruption. Therefore, it would seem that he was the first to assert two contrary principles, good and evil, as Aristotle says in Metaphysics 1.¹

Pythagoras asserted two primaries, good and evil: not as active principles, however, but as formal. For he stated that these two are the genera under which all other things are comprised, as the Philosopher declares in Metaphysics 1.¹

Now, though these errors of the earlier philosophers were refuted by those of later times, certain men of perverted sense have presumed to combine them with Christian doctrine. The first of these was Marchius¹—from whom the Marchians take their name—who, under the guise of a Christian, founded a heresy, holding the existence of two contrary principles. He was followed by the Cerdonians, afterwards by the Marchianists, and lastly by the Manicheans, who especially spread this error abroad.

That the first cause of the distinction of things is not the order of secondary agents

We may also prove from the same premises that the distinction of things is not caused by the order of secondary agents, as those maintained who held that God, since he is one and simple, produces but one effect, which is the first created substance: and that this, because it cannot equal the simplicity of the first cause—not being pure act, but having a certain admixture of potency—has a certain multiplicity, so that it is able to produce some kind of plurality; and that in this way, effects always failing of the simplicity of their causes, the multiplication of effects results in the diversity of the things of which the universe consists.

Accordingly, this opinion does not assign one cause to the entire diversity of things, but a different cause to each particular effect, and the entire diversity of things it ascribes to the concurrence of all causes. Now we say that those things happen by chance which result from the concurrence of various causes, and not from one determinate cause. Therefore, the distinction of things and the order of the universe would be the result of chance.

Moreover. That which is best in caused things is reduced to that which is best in causes as to its first cause: for effects must be proportionate to their causes.¹ Now the best among all things caused is the order of the universe, in which the good of the universe consists, even as in human affairs the good of the nation is more God-like than the good of the individual.² Hence we must reduce the order of the universe to God as its proper cause, whom we have proved above³ to be the highest good. Therefore, the distinction of things, in which the order of the universe consists, is the result not of secondary causes, but rather simplicity of the first cause.

Further. It seems absurd to assign a defect in things as cause of that which is best in things. Now the best in things caused is their distinction and order, as shown above.¹ Therefore, it is unreasonable to assert that this distinction is the result of secondary causes failing of the simplicity of the first cause.

Again. In all ordered active causes, where action is directed to an end, the ends of the secondary causes must be directed to the end of the first cause: thus the ends of the arts of war, horsemanship, and bridle-making are directed to the end of the political art.¹ Now the origin of beings from the first being is by an action directed to an end, since it is according to intellect, as we have proved,² and every intellect acts for an end. If, therefore, in the production of things there are any secondary causes, it follows that their ends and actions are directed to the end of the first cause, which is the last end in things caused. And this is the distinction and order of the parts of the universe, which order is the ultimate form, so to speak. Therefore, the distinction and order in things is not on account of the actions of secondary causes, but rather the actions of secondary causes are on account of the order and distinction to be established in things.

Further. If the distinction of the parts of the universe and their order is the proper effect of the first cause—as being the ultimate form and the greatest good in the universe—it follows that the distinction and order of things must be in the intellect of the first cause. For in things that are made by an intellect, the form produced in the things made proceeds from a like form in the intellect: for instance, the house which exists in matter proceeds from the house which is in an intellect. Now the form of distinction and order cannot be in an active intellect, unless the forms of the things which are distinct and ordered be in it. Therefore, in the divine intellect there are the forms of various things distinct and ordered, nor is this incompatible with his simplicity, as we have proved above.¹ Accordingly, if things that are outside the mind proceed from forms that are in the intellect, it will be possible, in things that are effected by an intellect, for many and diverse things to be caused immediately by the first cause, notwithstanding the divine simplicity, on account of which some fell into the aforesaid opinion.

Again. The action of one who acts by intellect terminates in the form which he understands, and not in another, except accidentally and by chance. Now God is an agent by his intellect, as we have proved:¹ nor can his action be affected by chance, since he cannot fail of his action.² It follows, therefore, that he produces his effect for the very reason that he understands and intends that same effect. But by the same idea that he understands one effect, he can understand many effects other than himself. Therefore, he can cause many things at once, without any intermediary.

Moreover. As we have shown above,¹ the power of God is not confined to one effect, and this suits his simplicity, because the more a power is united, the nearer it approaches to infinity, being able to extend to so many more things. But it does not follow that one thing only can be made by one, except when the agent is determined to one effect. Therefore, we are not bound to conclude that, because God is one and utterly simple, many things cannot proceed from him except by means of certain things that fail of his simplicity.

Hence it is said: in the beginning God created the heavens and the earth (Gen 1:1); and: perhaps you can, like him, spread out the heavens, hard as molten brass? (Job 37:18).

By the foregoing we exclude the opinion of Avicenna,¹ who says that God, by understanding himself, produced one first intelligence, in which there is already potency and act; that this, through understanding God, produces the second intelligence; through understanding itself as being in act, this produces the soul of the sphere; and through understanding itself as being in potency, it produces the substance of the first sphere. And thus starting from this point he explains the causing of the diversity of things by secondary causes.

We also exclude the opinion of certain early heretics who said that not God but the angels created the world: of which error Simon Magus is said to have been the original author.

That the distinction among things does not result from some secondary agent introducing various forms into matter

Certain modern heretics say that God created the matter of all visible things, but that this was diversified with various forms by an angel. The falseness of this opinion is evident.

For the heavenly bodies, in which no contrariety is to be found, cannot have been formed from any matter, since whatever is made from preexisting matter must be made from a contrary. Therefore, it is impossible that any angel should have formed the heavenly bodies from matter previously created by God.

Moreover. The heavenly bodies either have no matter in common with the lower bodies, or they only have prime matter in common with them. For the heaven neither is composed of elements, nor is of an elemental nature, which is proved by its movement, which differs from that of all the elements. And prime matter could not by itself precede all formed bodies, since it is nothing but pure potency, and all actual being is from some form. Therefore, it is impossible that an angel should have formed all visible bodies from matter previously created by God.

Again. Everything that is made, is made to be, since making is the way to being. To each thing caused, therefore, it is becoming to be made as it is becoming to be. Now being is not becoming to form alone, nor to matter alone, but to the composite: for matter is merely in potency, while form is that by which a thing is, since it is act. Hence it follows that the composite, properly speaking, is. Therefore, it belongs to it alone to be made, and not to matter without form. Therefore, there is not one agent that creates matter only, and another that induces the form.

Again. The first induction of forms into matter cannot be from an agent acting by movement only, for all movement towards a form is from a determinate form towards a determinate form, because matter cannot be without all form, and thus some form is presupposed in matter. But every agent intending a merely material form must be an agent by movement: For, since material forms are not subsistent of themselves, and their being is to be in matter, they cannot be brought into being except either by the production of the whole composite, or by the transmutation of matter to this or that form. Therefore, it is impossible that the first induction of forms into matter be from someone creating the form only, but it must be from him who is the Creator of the whole composite.

Further. Movement towards a form comes naturally after local movement: for it is the act of that which is more imperfect, as the Philosopher proves.¹ Now in the natural order, things that come afterwards are caused by those which come before. Hence movement towards a form is caused by local movement. But the first local movement is the movement of the heaven. Therefore, all movement towards a form takes place through the means of the heavenly movement. Hence those things that cannot be made through the means of the heavenly movement cannot be made by an agent which can only act by movement, and such must be the agent that cannot act except by inducing form into matter, as we have proved.² Now many sensible forms cannot be produced by the heavenly movement except by means of certain presupposed determinate principles: thus certain animals are not made except from seed. Therefore, the original production of these forms, for producing which the heavenly movement is not sufficient without the preexistence of those forms in the species, must proceed from the Creator alone.

Again. Just as local movement of part and whole are the same, like that of the whole earth and of one clod,¹ so the change of generation is the same in the part and in the whole. Now the parts of those things that are subject to generation and corruption are generated by acquiring actual forms from forms in matter, and not from forms existing outside matter, since the generator must be like the thing generated, as the Philosopher proves in Metaphysics 7.² Neither, therefore, can the total acquisition of forms by matter be effected by any separate substance, such as an angel, but this must be done either by means of a corporeal agent or by a creative agent which acts without movement.

Further. Even as being is first among effects, so does it correspond to the first cause as its proper effect. Now being is by form and not by matter. Therefore, the first causation of forms is to be ascribed especially to the first cause.

Moreover. Since every agent produces its like, the effect obtains its form from that to which it is likened by the form it acquired, even as the material house acquires its form from the art, which is the likeness of the house in the mind. Now all things are like God, who is pure act, inasmuch as they have forms by which they become actual, and inasmuch as they desire forms, they are said to desire the divine likeness.¹ Therefore, it is absurd to say that the formation of things belongs to another than God the Creator of all.

Hence it is that in order to exclude this error, Moses, after saying that in the beginning God created the heavens and the earth (Gen 1:1), added how he distinguished all things by forming them in their respective species. Moreover, the Apostle says that in Christ all things were created, in heaven and on earth, visible and invisible (Col 1:16).

That distinction among things did not result from the diversity of merits or demerits

It remains now for us to show that the distinction among things did not result from different movements of the free will of rational creatures, as Origen maintained in his Peri Archon.¹ For he wished to refute the objections and errors of the early heretics, who strove to prove that the different nature of good and evil in things is owing to contrary agents. But on account of the great difference which he observed both in natural and in human things, which difference apparently is not preceded by any merits—for instance, that some bodies are white, some dark, that some are born of pagans, some of Christians—he was compelled to assert that all differences to be found in things have proceeded from a difference of merits, in accordance with the justice of God. For he says that God, of his mere goodness, first made all creatures equal, all of them being spiritual and rational, and these by their free will were moved in diverse ways, some adhering to God more, and some less, some withdrawing from God more, and some less. In this way, there resulted various grades in spiritual substances through divine justice, so that some were angels in their various orders, some human souls in their various states, some demons in their various states. On account of the diversity among rational creatures, he said that God had established diversity among corporeal creatures, so that the more noble spiritual substances were united to the more noble bodies, and thus the corporeal creature would minister in all other various ways to the diversity of spiritual substances.

But this opinion is clearly convicted of falsehood. For among effects, the better a thing is, the more does it obtain precedence in the intention of the agent. Now the greatest good in things created is the perfection of the universe, consisting in the order of distinct things, because in all things the perfection of the whole takes precedence of the perfection of each part. Therefore, the diversity of things results from the principal intention of the first agent, and not from a diversity of merits.

Again. If all rational creatures were created equal from the beginning, we must say that one of them does not depend on another in its action. Now that which results from the concurrence of various causes, one of which does not depend on another, is casual. Therefore, according to the aforesaid opinion, this distinction and order of things is casual: and this is impossible, as proved above.¹

Moreover. That which is natural to a person is not acquired by him by his will, for the movement of the will, or free will, presupposes the existence of the willer, and for this his nature is required. Accordingly, if the various grades of rational creatures were derived from a movement of the free will, all rational creatures would have their respective grade not naturally, but accidentally. But this is impossible. For, since the specific difference is natural to each thing, it would follow that all created rational substances—namely, angels, demons, human souls, and the souls of the heavenly bodies (which Origen supposed to be animated)—are of one species. That this is false is proved by the diversity of natural actions, because the mode by which the human intellect naturally understands is not the same as that which sense and imagination, or the angelic intellect and the soul of the sun demand—unless perhaps we picture the angels and heavenly bodies with flesh and bones and like parts, so that they may have organs of sense, which is absurd. It follows, therefore, that the diversity of intellectual substances is not the result of a diversity of merits, which are according to movements of the free will.

Again. If things that are natural are not acquired by a movement of the free will, in contrast, the union of a rational soul with such a body is acquired by the soul on account of preceding merit or demerit according to the movement of the free will, it would follow that the union of this soul with this body is not natural. Therefore, neither is the composite natural. Yet man and the sun and the stars, according to Origen, are composed of rational substances and such and such bodies. Therefore, all these things which are the noblest of corporeal substances are unnatural.

Again. If the union of this rational substance with this body is becoming to this rational substance not as such a substance, but as having so merited, its union with this body is not an essential but an accidental union. Now, a species does not result from things united accidentally, because from such a union there does not result a thing essentially one: for “white man” or “clothed man” is not a species. It would follow, therefore, that man is not a species, nor yet the sun, nor the moon, nor anything of the kind.

Moreover. Those things which result from merit may be changed for better or for worse, because merits and demerits may increase or diminish, especially according to Origen, who said that the free will of every creature is always flexible to either side. Therefore, if a rational soul has been allotted this body on account of preceding merit or demerit, it will follow that it can be united again to another body, and not only that the human soul takes another human body, but also that it may sometimes take a sidereal body, which is in accordance with the Pythagorean fable, that any soul enters any body.¹ This is both erroneous according to philosophy—which teaches that determinate matters and movables are allotted to determinate forms and movers—and heretical according to faith, which declares that in the resurrection the soul resumes the same body which it has left.

Again. Every distinction is either according to a division of quantity, which is only in bodies—therefore, according to Origen, it could not be in the bodies first created—or according to formal division. But this latter cannot be without distinction of grades, since such a distinction is reduced to that of privation and form: and thus one of the condivided forms must be better and the other less good. Hence, according to the Philosopher,¹ the species of things are like numbers, one of which is in addition to or in subtraction from the other. Accordingly, if there were many rational substances created from the beginning, there must have been a distinction of grades among them.

Again. If rational creatures can subsist without bodies, there was no need to set up a distinction in the corporeal nature on account of the various merits of rational creatures, since even without a diversity of bodies it was possible to find various grades in rational substances. And if rational substances cannot subsist without bodies, it follows that the corporeal creature also was formed from the beginning together with the rational creature. Now, the corporeal creature is further removed from the spiritual than spiritual creatures are from one another. If, therefore, from the beginning God established such a great distance among his creatures without any previous merits, there was no need for a difference of merits to precede in order that rational creatures should be established in different grades.

Further. If the diversity of corporeal creatures corresponds to the diversity of spiritual creatures, for the same reason the uniformity of corporeal nature would correspond to the uniformity of rational creatures. Therefore, the corporeal nature would have been created even if the preceding merits of the rational creature had been not different, but uniform. Hence prime matter would have been created, which is common to all bodies, but under one form only. But in it there are many forms in potency. Therefore, it would have remained imperfect, its one form alone being reduced to act: and this is unbefitting the divine goodness.

Again. If the diversity of the corporeal creature results from the different movements of the rational creature’s free will, we shall have to say that the reason why there is only one sun in the world is because only one rational creature was moved by its free will in such a way as to merit to be united to such a body. Now, it was by chance that only one sinned thus. Therefore, it is by chance that there is only one sun in the world, and not for the need of corporeal nature.

The authority of Sacred Scripture is in evident contradiction with this error. For in each making of visible creatures Moses speaks in terms such as these: God saw that it was good (Gen 1:9), and afterwards in reference to all, he adds: God saw everything that he had made, and it was very good (Gen 1:31). Hence we are clearly given to understand that the corporeal and visible creatures were made because it is good for them to be, and this is in keeping with the divine goodness, and not on account of any merits or sins of rational creatures.

Origen seems not to have taken into consideration that when we give a thing not as a due, but as a free gift, it is not contrary to justice if we give unequal things without weighing the difference of merits, since payment is due to those who merit. Now God, as stated above,¹ brought things into being not as though it were due to them, but out of mere bounty. Therefore, the diversity of creatures does not presuppose diversity of merits.

Again, since the good of the whole is better than the good of each part, it does not befit the best maker to lessen the good of the whole in order to increase the good of some of the parts: thus a builder does not give to the foundation the goodness which he gives to the roof, lest he should make a house in ruins. Therefore, God, the maker of all, would not make the whole universe the best of its kind if he made all the parts equal, because many degrees of goodness would be wanting to the universe, and thus it would be imperfect.

What is in truth the first cause of the distinction of things

From what we have said it may be shown what is truly the first cause of the distinction of things.

Since every agent intends to induce its likeness into its effect, as far as the effect can admit of it, it does this the more perfectly according as it is more perfect itself: for it is clear that the hotter a thing is, the hotter it makes a thing, and the better the craftsman, the more perfectly he induces the form of his art into matter. Now God is the most perfect agent. Therefore, it belonged to God to induce his likeness into created things most perfectly, as far as is befitting to a created nature. But created things cannot come by a perfect likeness to God with respect to only one species of the creature, for, since the cause surpasses its effect, that which is simply and unitedly in the cause is found in the effect to have a composite and multiple nature—unless the effect reach to the species of the cause, which does not apply to the case in point, since the creature cannot be equal to God. Therefore, there was need for multiplicity and variety in things created, in order that we might find in them a perfect likeness to God according to their mode.

Moreover. Just as things made of matter are in the passive potency of matter, so things made by an agent must be in the active potency of the agent. Now the passive potency of matter would not be perfectly reduced to act if only one of those things to which matter is in potency were reduced to act. Therefore, if an agent, whose potency embraces several effects, were to make only one of them, its potency would not be so perfectly reduced to act as when it makes several. Now, the effect receives the likeness of the agent by the active potency being reduced to act. Therefore, there would not be a perfect likeness of God in the universe if all things were of one degree. For this reason, therefore, there is distinction in created things: in order that they may receive God’s likeness more perfectly by multiplicity than by unity.

Further. A thing approaches the more perfectly to God’s likeness, according as it is like him in more things. Now in God is goodness, and the outpouring of that goodness into other things. Therefore, the creature approaches more perfectly to God’s likeness if it is not only good, but can also act for the goodness of other things, than if it were merely good in itself, even as that which both shines and enlightens is more like the sun than that which only shines. Now a creature would be unable to act for the goodness of another creature unless in creatures there were plurality and inequality, because the agent is distinct from and more noble¹ than the patient. Therefore, it was necessary that there be also different species of things, and consequently different degrees in things.

Again. A plurality of goods is better than one finite good, since they contain this and more besides. Now all goodness of the creature is finite, for it fails of God’s infinite goodness. Therefore, the universe of creatures, if they are of many degrees, is more perfect than if things were of but one degree. But it becomes the highest good to make what is best. Therefore, it was becoming that it should make many degrees of creatures.

Further. The goodness of the species surpasses the good of the individual, even as the formal exceeds that which is material. Hence multitude of species adds more to the goodness of the universe than multitude of individuals in one species. Therefore, it concerns the perfection of the universe, that there be not only many individuals, but that there be also different species of things, and consequently different degrees in things.

Again. Whatever acts by intellect reproduces the species of its intellect in the thing made, for thus an agent by art produces his like. Now God made the creature as an agent by intellect and not by a necessity of his nature, as we proved above.¹ Therefore, the species of God’s intellect is reproduced in the creature made by him. But an intellect that understands many things is not sufficiently reproduced in one only. Since, then, the divine intellect understands many things, as was proved in the first book,² it reproduces itself more perfectly if it produces many creatures of all degrees than if it had produced one only.

Moreover. Supreme perfection should not be wanting to a work made by the supremely good workman. Now the good of order among diverse things is better than any one of those things that are ordered taken by itself: for it is formal in respect of each as the perfection of the whole in respect of the parts. Therefore, it was unbecoming that the good of order should be wanting to God’s work. Yet this good could not be if there were no diversity and inequality of creatures.

Accordingly, there is diversity and inequality in things created, not by chance,¹ not as a result of a diversity of matter,² not on account of certain causes,³ or merits⁴ intervening, but from God’s own intention, in that he willed to give the creature such perfection as it was possible for it to have.

Hence it is said: God saw everything that he had made, and behold, it was very good (Gen 1:31), after it had been said of each that they are good. For each one in its nature is good, but all together are very good, on account of the order of the universe, which is the ultimate and noblest perfection in things.

Intellectual creatures

That for the perfection of the universe it was necessary that there should be some intellectual creatures

Such being the cause of diversity among things, it remains for us to inquire into the diverse things as far as this concerns the truth of faith: for this was the third thing we proposed to do.¹ We shall show, first, that as a result of the divine ordinance allotting to creatures that perfection which is best in keeping with their mode, certain creatures were made intellectual so as to occupy the highest point in the universe.

For an effect is most perfect when it returns to its source: hence of all figures the circle, and of all movements the circular, are the most perfect, because in them a return is made to the beginning. Hence, in order that the universe of creatures may attain its ultimate perfection, creatures must return to their principle. Now each and every creature returns to its principle insofar as it bears a likeness to its principle, in keeping with its being and nature, in which it has a certain perfection, even as all effects are most perfect when they are most like their effective cause, as a house when it is most like art, and fire when it is most like its generator. Since, then, God’s intellect is the principle of the creature’s production, as we proved above,¹ it was necessary for the creature’s perfection that some creatures should be intelligent.

Moreover. Second perfection in things adds to first perfection. Now, as the being and nature of a thing is considered as pertaining to its first perfection, so is operation considered as belonging to its second perfection. Therefore, for the complete perfection of the universe, there should be some creatures which return to God not only in likeness of nature, but also by their operation. And this cannot be save by the act of the intellect and will, since not even God himself has any other operation towards himself than these. Therefore, it was necessary for the greatest perfection of the universe that there should be some intellectual creatures.

Further. In order that creatures might render perfectly a representation of the divine goodness, it was necessary, as above stated,¹ that things should not only be made good, but also that they should operate for the goodness of others. Now a thing is perfectly likened to another in its operation when the action is not only of the same species, but also the mode of acting is the same. Hence it was necessary for the highest perfection of things that there should be some creatures who act in the same way as God. But it has been proved above² that God acts by intellect and will. Therefore, it was necessary for some creatures to have intelligence and will.

Moreover. Likeness of the effect to its efficient cause is considered on the part of the effect’s form which preexists in the agent: for an agent produces its like as regards the form by which it acts. Now the form of the agent is received in the effect sometimes indeed according to the same mode of being as it has in the agent (thus the form of the fire generated has the same mode of being as the form of the generating fire), and sometimes according to another mode of being (thus the form of the house, which exists intelligibly in the craftsman’s mind, is received in the house that is outside the mind according to a material manner): and it is clear that the former likeness is more perfect than the latter. Now, the perfection of the universe of creatures consists in a likeness to God, just as the perfection of every effect consists in a likeness to its efficient cause. Therefore, the highest perfection of the universe requires not only the second likeness of the creature to God, but also the first, as far as possible. But the form by which God produces the creature is an intelligible form in him, since he is an agent by intellect, as proved above.¹ Therefore, the highest perfection of the universe requires that there should be some creatures in which the form of the divine intellect is reproduced according to an intelligible mode of being, and this means that there should be creatures of an intellectual nature.

Again. Nothing but his goodness moves God to the production of creatures, which goodness he wished to communicate to other things by way of likeness to himself, as shown above.¹ Now likeness to another is found in a thing in two ways: in one way, as regards natural being, as the likeness of fiery heat is in the thing heated by fire; in another way, as regards knowledge, as the likeness of fire is in sight or touch. In order, therefore, that the likeness of God might be in things in such ways as are possible, the divine goodness must be communicated by likeness not only in being but also in knowledge. But only an intellect is capable of knowing the divine goodness. Therefore, it was necessary that there should be intellectual creatures.

Further. In all things suitably ordered, the relation of second to last imitates the order of first to all both second and last, though sometimes defectively. Now it has been proved¹ that God comprises all creatures in himself. And this is reproduced in corporeal creatures, although in a different way: for the higher body is always found to comprise and contain the lower, yet according to quantitative extension. But God contains all creatures in a simple manner, and not by extension of quantity. Hence, so that creatures might not lack the imitation of God in this way, intellectual creatures were made that comprise and contain the lower not according to quantitative extension, but simply by way of intelligibility, since what is understood is in the intelligent subject, and is grasped by his intellectual operation.

That intellectual substances are capable of willing

Now these intellectual substances must be capable of willing.

For there is in all things a desire for good, since the good is what all desire, as philosophers teach.¹ This desire, in things devoid of knowledge, is called natural appetite: thus a stone desires to be below. In those which have sensitive knowledge, it is called animal appetite, which is divided into concupiscible and irascible. In those which understand, it is called intellectual or rational appetite, which is the will. Therefore, intellectual substances have a will.

Again. That which is by another is reduced to that which is by itself as preceding it; and hence, according to the Philosopher in Physics 8,¹ things moved by another are reduced to the first self-movers. Also, in syllogisms, the conclusions which are known from other things are reduced to self-evident first principles. Now, in created substances, we find some which do not move themselves to act, but are moved by force of nature: for instance, inanimate things, plants and dumb animals, for it is not in them to act or not to act. Therefore, there must be a reduction to some first things which move themselves to action. But the first in created things are intellectual substances, as shown above.² Therefore, these substances move themselves to act. Now this is proper to the will, by which a substance has the dominion of its action, because it is in it to act and not to act. Therefore, created intellectual substances have a will.

Moreover. The principle of every operation is the form by which a thing is actual, since every agent acts insofar as it is actual. Therefore, the mode of an operation consequent upon a form must be in accordance with that form. Hence a form that does not proceed from that which acts by that form causes an operation over which the agent has no dominion, but if there be a form that proceeds from that which acts by it, the agent will have dominion over the consequent operation. Now natural forms, upon which natural movements and operations are consequent, do not proceed from those things whose forms they are, but wholly from extrinsic agents, since by a natural form a thing has being in its own nature, and nothing can be cause of its own being. Therefore, things that are moved naturally do not move themselves: for a heavy body does not move itself downwards, but its generator, which gave it its form.¹

Again, in dumb animals, the forms, sensed or imagined, which result in movement are not discovered by the dumb animals themselves, but are received by them from exterior sensibles which act on their senses, and judged of by their natural estimative faculty. Hence, though they are said to move themselves after a fashion (insofar as one part of them moves, and another is moved), yet the actual moving is not from themselves, but partly from external objects sensed, and partly from nature. For insofar as their appetite moves their members, they are said to move themselves, in which they surpass inanimate beings and plants; and insofar as the act of their appetite is in them a necessary sequel to the forms received through their senses and the judgment of their natural estimative power, they are not the cause of their own movement. Hence they have not dominion over their own action. But the form understood, by which the intellectual substance acts, proceeds from the intellect itself, being conceived and, after a fashion, thought out by it. This may be seen in the form of art, which the craftsman conceives and thinks out, and by which he works. Accordingly, intellectual substances move themselves to act as having dominion over their actions. Therefore, they have a will.

Again. The active force should be proportionate to the patient, and motive power to the movable. Now in things possessed of knowledge, the apprehensive power is related to the appetitive, as the motive power to the movable, since that which is apprehended by the sense, imagination, or intellect moves the intellectual or animal appetite. But intellective apprehension is not confined to certain objects, but is of all things: hence the Philosopher says in On the Soul 3 of the passive intellect that it is that by which we become all things.¹ Hence the appetite of an intellectual substance has a habitude to all things. Now it is proper to the will to have a habitude to all things: hence the Philosopher says in Ethics 3 that it is of both the possible and the impossible.² Therefore, intellectual substances have a will.

That intellectual substances are of free will in acting

From this it is clear that the aforesaid substances are of free will¹ in acting.

That they act by judgment is clear, since through their intellective knowledge they judge of things to be done. And they must have freedom if, as proved,¹ they have dominion over their action. Therefore, the aforesaid substances are of free will in acting.

Again. The free is that which is its own cause.¹ Therefore, that which is not the cause of its own acting is not free in acting. Now whatever things are not moved, nor act except they be moved by others, are not a cause of their own acting. Therefore, self-movers alone have liberty in acting. These alone act by judgment, for the self-mover is divided into mover and moved, and the mover is the appetite moved by intellect, imagination, or sense, to which faculties judgment belongs. Of these, then, those alone judge freely which move themselves in judging. Now, no judging power moves itself to judge unless it reflects on its own action, for if it moves itself to judge it must know its own judgment: and this belongs to the intellect alone. Hence irrational animals have, in a sense, free movement or action, but not free judgment: but inanimate beings, which are moved only by others, do not have even free action or movement, while intellectual beings have freedom not only of action, but also of judgment, and this is to have free will.

Further. The apprehended form is a moving principle according as it is apprehended under the aspect of good or fittingness, because the external action in self-movers comes from the judgment by which it is judged that something is good or fitting through the aforesaid form. Accordingly, if he who judges moves himself to judge, he must move himself to judge by some higher apprehended form. And this form can be no other than the idea itself of good or fittingness, by which one judges of any determinate good or fitting thing. Therefore, those alone move themselves to judge who apprehend the common notion of goodness or fittingness. And these are intellectual beings alone. Therefore, intellectual beings alone move themselves not only to act, but also to judge. Therefore, they alone are free in judging, and this is to have free will.

Moreover. Movement and action do not follow from a universal concept save through the medium of a particular apprehension, for movement and action are about particular things. Now the intellect is naturally apprehensive of universals. Therefore, so that movement and action of any kind follow from the apprehension of the intellect, it is necessary for the universal concept of the intellect to be applied to particulars. But the universal contains many particulars potentially. Hence application of the intellectual concept may be made to many and diverse things. Consequently, the judgment of the intellect about matters of action is not determined to one thing only. Therefore, all intellectual beings have free will.

That the intellectual substance is not a body

From the foregoing it is shown that no intellectual substance is a body.

For no body is found to contain anything except by quantitative commensuration: therefore, if a thing contain a whole thing in the whole of itself, each part will contain a part, the greater part a greater part, and the lesser part a lesser part. But an intellect does not contain a thing understood by quantitative commensuration, because by its whole self it understands and comprehends both whole and part, things both great and small in quantity. Therefore, no intelligent substance is a body.

Moreover. No body can receive the substantial form of another body unless it lose its own form by corruption. But an intellect is not corrupted by receiving the forms of all bodies, but rather is perfected, since it is perfected by understanding, and understands by having in itself the forms of things understood. Therefore, no intellectual substance is a body.

Further. The principle of distinction between individuals of the same species is the division of matter in respect of quantity, for the form of this fire differs not from the form of that fire, except by the fact of its being in different parts into which matter is divided; nor is this otherwise than by division of quantity, without which substance is indivisible. Now that which is received into a body is received into it according to quantitative division. Therefore, a form is not received into a body, except as individualized. If, therefore, an intellect were a body, the intelligible forms of things would not be received into it except as individualized. But the intellect understands things by their forms which it has at its disposal. Consequently, the intellect would not understand universals, but only particulars. Now this is clearly false. Therefore, no intellect is a body.

Again. Nothing acts except in accordance with its species, because the form is the principle of action in everything. If, therefore, an intellect be a body, its action will not transcend the order of bodies. Therefore, it would understand nothing but bodies. Now this is clearly false, since we understand many things that are not bodies. Therefore, the intellect is not a body.

Again. If an intelligent substance is a body, it is either finite or infinite. Now, it is impossible for a body to be infinite actually, as is proved in the Physics.¹ Therefore, it is a finite body, if we suppose it to be a body at all. But this is impossible, since in no body can there be infinite power, as we have proved above.² Now the power of the intellect in understanding is in a manner infinite, for by adding, it understands species of numbers to infinitude, and likewise species of figures and proportions. Moreover, it knows the universal, which is virtually infinite in its compass, since it contains individuals which are potentially infinite. Therefore, the intellect is not a body.

Moreover. It is impossible for two bodies to contain one another, since the container exceeds the contained. Yet two intellects contain and comprehend one another, when one understands the other. Therefore, the intellect is not a body.

Again. No body’s action reflects on the agent: for it is proved in the Physics¹ that no body is moved by itself except in respect of a part (namely, so that one of its parts be mover and the other moved). Now the intellect by its action reflects on itself, for it understands itself not only as to a part, but as to the whole. Therefore, it is not a body.

Again. A body’s action is not the object of that body’s action, nor is its movement the object of its movement, as proved in the Physics.¹ But the action of the intellect is the object of its action: for just as the intellect understands a thing, so does it understand that it understands, and so on indefinitely. Therefore, an intellectual substance is not a body.

Hence it is that Sacred Scripture calls intellectual substances “spirits,” in which way it is accustomed to name God, who is incorporeal: God is a spirit (John 4:24). And it is said: for in her, namely divine wisdom, is the spirit of understanding, containing all intelligible spirits¹ (Wis 7:23).

By this is excluded the error of the early natural philosophers, who held that there was none but corporeal substance: therefore, they said that even the soul is a body, either fire, air, or water, or something of the kind.¹

Which opinion some have endeavored to introduce into the Christian faith, by saying that the soul is the effigy of a body, like a body outwardly imitated.

That intellectual substances are immaterial

It follows from this that intellectual substances are immaterial.

For everything composed of matter and form is a body, since matter cannot receive various forms except in respect of its various parts. And this diversity of parts cannot be in matter, except insofar as common matter is divided into several by the dimensions existing in matter: for without quantity substance is indivisible. Now it has been proved¹ that no intelligent substance is a body. It follows, therefore, that it is not composed of matter and form.

Moreover. Just as man does not exist apart from this man, so matter exists not apart from this matter. Accordingly, whatever subsistent thing is composed of matter and form is composed of individual form and matter. Now the intellect cannot be composed of individual matter and form. For the species of things understood become actually intelligible through being abstracted from individual matter. And according as they are actually intelligible, they become one with the intellect.¹ Therefore, the intellect also must be without individual matter. Therefore, the intelligent substance is not composed of matter and form.

Further. The action of anything composed of matter and form belongs not to the form alone, nor to the matter alone, but to the composite: because to act belongs to that which has being, and being belongs to the composite through its form. Therefore, the composite also acts through its form. Accordingly, if the intelligent substance be composed of matter and form, to understand will be the act of the composite. But action terminates in a thing like the agent; therefore, the composite in generating produces not a form but a composite. If, therefore, to understand be an action of the composite, it would understand neither form nor matter, but only the composite. Therefore, the intelligent substance is not composed of matter and form.

Again. The forms of sensible things have a more perfect being in the intellect than in sensible things, since they are more simple and extend to more objects: for by the one intelligible form of man, the intellect knows all men. Now a form existing perfectly in matter makes a thing to be actually such (for instance, to be fire or to be colored): if it does not make a thing to be actually such, it is in that thing imperfectly (for instance, the form of heat in the air that carries it, and the power of the first agent in its instrument). Consequently if the intellect were composed of matter and form, the forms of the things understood would make the intellect to be actually of the same nature as that which is understood. And this leads to the error of Empedocles, who said that the soul knows fire by fire, and earth by earth,¹ and so on. But this is clearly unreasonable. Therefore, the intelligent substance is not composed of matter and form.

Again. Forms of contraries, according to the being which they have in matter, are contrary: hence they exclude one another. But according as they are in the intellect they are not contrary: in fact one contrary is the intelligible ratio of the other, since one is understood through the other. Consequently, they do not have a material being in the intellect. Therefore, the intellect is not composed of matter and form.

Further. Matter does not receive a fresh form except by movement or change. But the intellect is not moved through receiving forms; rather is it perfected and is at rest while understanding, but its understanding is hindered by movement.¹ Consequently, forms are not received by the intellect as by matter or a material thing. Therefore, it is clear that intelligent substances are immaterial as well as incorporeal.

Hence Dionysius says: on account of the rays of the divine goodness, all intellectual substances are subsistent, and are known to be both incorporeal and immaterial.¹

That the intellectual substance is not a material form

From the same premises it may be shown that intellectual natures are subsistent forms, and do not exist in matter as though their being depended on matter.

For forms dependent on matter, as regards their being properly speaking, do not have being themselves, but the composites through them. Hence, if intellectual substances were forms of this kind, it would follow that they have material being, just as they would if they were composed of matter and form.

Again. Forms that do not subsist of themselves cannot act of themselves, but the composites act through them. If, therefore, intellectual natures were forms of this kind, it would follow that they do not themselves understand, but the things composed of them and matter. Consequently, an intelligent being would be composed of matter and form. And this has been proved¹ to be impossible.

Moreover. If the intellect were a form in matter and not self-subsistent, it would follow that what is received into the intellect is received into matter, for such forms as have their being tied to matter do not receive anything without its being received into matter. Since, then, the reception of forms into the intellect is not a reception of forms into matter, it is impossible that the intellect be a material form.

That in created intellectual substances there is a difference between being and what is

Now, although intellectual substances are not corporeal, nor composed of matter and form, nor existing in matter as material forms, we must not think that they equal the divine simplicity. For a certain composition is to be found in them from that “being” in them is not the same as “what is.’

For if being is subsistent, nothing besides being is added to it. For even in those things whose being is not subsistent, that which is in an existing thing beside its being is indeed united to the existing thing, but it is not one with its being, except accidentally, insofar as there is one subject having being and that which is beside being: thus it is clear that in Socrates, beside his substantial being, there is white, which is distinct from his substantial being, since to be Socrates and to be white are not the same, save accidentally. Consequently, if being is not in a subject, there will remain no way in which that which is beside being can be united to it. Now being, as being, cannot be diverse, but it can be differentiated by something beside being: thus the being of a stone is other than the being of a man. Hence that which is subsistent being can be one only. Now it was shown above¹ that God is his own subsistent being: hence nothing beside him can be its own being. Therefore, in every substance beside him, the substance itself must be distinct from its being.

Moreover. A common nature, if considered in the abstract, can only be one—although those that have that nature may be found to be many. For if the nature of animal subsisted as separate by itself, it would not have the things belonging to a man or to an ox. Now if we remove the differences which constitute a species, there remains the nature of the genus without division, since the same differences which divide the genus constitute the species. Accordingly, if being itself is common like a genus, a separate self-subsistent being can only be one. If, however, it be not divided by differences as a genus is, but by the fact that it is the being of this or that (as it is in truth), it is yet more evident that what exists of itself can only be one. It follows, therefore, since God is subsistent being, that nothing beside him is its own being.

Again. There cannot possibly be a twofold being absolutely infinite, for being that is absolutely infinite contains every perfection of being, so that if two things had such an infinity, there would be nothing in which they differed. Now subsistent being must be infinite, because it is not limited by any recipient. Therefore, there cannot be any subsistent being outside the first.

Again. If there is a self-subsistent being, nothing is applicable to it except that which belongs to a being as being. This is so because what is not said of a thing as such is only applicable to it accidentally, by reason of the subject: so that if we suppose it to be separated from its subject, it is in no way applicable to it. Now to be caused by another is not applicable to a being, as being: otherwise every being would be caused by another, and consequently we should have to proceed to infinity in causes, which is impossible, as shown above.¹ Therefore, that being which is subsistent must not be caused. Therefore, no caused being is its own being.

Moreover. The substance of a thing appertains to it of itself and not by another: therefore, to be actually lightsome is not of the air’s substance, since it comes to it from something else. Now every created thing has being from another, else it would not be caused. Therefore, in no created being is its being the same as its substance.

Again. Since every agent acts insofar as it is actual, it belongs to the first agent, which is most perfect, to be actual in the most perfect way. Now a thing is the more perfectly actual, the more its act is posterior in the order of generation, for act is posterior in time to the potency in the one and same subject which passes from potency to act. Also, act itself is more perfectly actual than that which has act, for the latter is actual on account of the former. Accordingly, these premises being supposed, it is clear from what has been already proved¹ that God alone is the first agent. Therefore, it belongs to him alone to be actual in the most perfect way—that is, to be the most perfect act. Now this is being, in which generation and all movement terminates, since every form and act is in potency before it acquires being. Therefore, it belongs to God alone to be his own being, just as it belongs to him alone to be the first agent.

Moreover. Being itself belongs to the first agent in respect of his proper nature: for God’s being is his substance, as we have proved above.¹ Now that which belongs to a thing in respect of its proper nature does not belong to others except by way of participation (like heat to bodies other than fire). Therefore, being itself belongs to all others except the first agent by a kind of participation. But that which belongs to a thing by participation is not its substance. Therefore, it is impossible that the substance of a thing other than the first agent should be being itself.

Hence the name proper to God is stated in Exodus 3:14 to be “he who is,” because it is proper to him alone that his substance is not distinct from his being.

That in created intellectual substances there is act and potency

From the foregoing it is evident that in created intellectual substances, there is composition of act and potency.

For in whatever thing we find two of which one is the complement of the other, the proportion of one of them to the other is as the proportion of potency to act, since nothing is completed save by its proper act. Now in the created intellectual substance we find two things, namely its substance and its being, which is not its very substance, as we have proved.¹ Now this very being is the complement of the existing substance, since a thing is actual by the fact that it has being. It follows, therefore, that in each of the aforesaid substances there is composition of act and potency.

Moreover. That which is received by a thing from an agent must be an act, since it belongs to an agent to make a thing actual. Now it was proved above¹ that all other substances have being from the first agent, and it is through having being from another that the substances thus caused exist. Consequently, being is in the caused substances as an act of theirs. But a potency is that in which there is act, since act as such refers to potency. Therefore, in every created substance there is potency and act.

Again. Everything which participates in a thing is compared to the thing participated as potency to act, since by that which is participated, the participator is made to be actually such. Now it was shown above¹ that God alone is essentially being, and all other things participate being. Therefore, every created substance is compared to its being as potency to act.

That composition of substance and being is not the same as composition of matter and form

Now composition of matter and form is not of the same nature as composition of substance and being, although both result from potency and act.

First, because matter is not the very substance of a thing—else it would follow that all forms are accidental, as the early natural philosophers maintained—but matter is part of the substance.

Second, because being itself is the proper act not of matter, but of the whole substance: for being is the act of that of which we can say that it is. Now being is said not of matter, but of the whole. Therefore, we cannot say of matter that it is, but the substance itself is that which is.

Third, because neither is the form being itself, but they are related as things in an order, because form is compared to being as light to enlightening, or whiteness to being white.

Also, because being itself is compared as act even to the very form. For in things composed of matter and form, the form is said to be the principle of being because it is the complement of substance, whose act being is, even as transparency is the principle of being lightsome to the air, in that it makes the air the proper subject of light.

Therefore, in things composed of matter and form, neither matter nor form, nor even being itself, can be described as that which is. Yet the form can be described as that by which it is, or as much as it is the principle of being. However, the whole substance is what is, and being is that by which the substance is called a being.

But in intellectual substances, which are not composed of matter and form, as shown above,¹ and in which the form itself is a subsistent substance, the form is what is, and being is the act whereby it is.

Consequently, in them there is but one composition of act and potency—namely, a composition of substance and being—which by some is said to be of what is and being, or of what is and whereby it is.

On the other hand, in things composed of matter and form there is a twofold composition of act and potency: the first, of the substance itself, which is composed of matter and form; the second, of the already composite substance and being, which composition can also be said to be of what is and being, or of what is and whereby it is.

It is, therefore, evident that composition of act and potency covers more ground than composition of form and matter. Therefore, matter and form divide a natural substance, while potency and act divide being in general. For this reason, whatever is consequent upon potency and act, as such, is common to created substances, whether material or immaterial; for instance, to receive and to be received, to perfect and to be perfected. But whatever things are proper to matter and form as such (for instance, to be generated, and to be corrupted, and so forth), are proper to material substances, and are in no way applicable to created immaterial substances.

That intellectual substances are incorruptible

From the foregoing it is clearly shown that every intellectual substance is incorruptible.

For all corruption consists in separation of form from matter: simple corruption from separation of the substantial form, relative corruption from separation of an accidental form. For the thing must exist so long as the form remains, since by the form the substance is made the proper recipient of being. But where there is not composition of form and matter, there can be no separation of the same: therefore, neither can there be corruption. Now it has been proved¹ that no intellectual substance is composed of matter and form. Therefore, no intellectual substance is corruptible.

Moreover. That which belongs to a thing essentially is necessarily in it always and inseparably: thus roundness is essentially in a circle and accidentally in a coin; therefore, it is possible for a coin to be made not round, whereas it is impossible for a circle not to be round. Now, being is an essential consequence of form, for “essential” means according as it is such,¹ and a thing has being according as it has a form. Hence substances that are not themselves forms can be deprived of being insofar as they lose a form, just as a coin is deprived of roundness according as it ceases to be round. However, substances that are themselves forms can never be deprived of being: thus if a circle were a substance, it could never be made not round. Now, it was shown above² that intellectual substances are themselves subsistent forms; therefore, they cannot possibly cease to exist, and consequently they are incorruptible.

Further. In every corruption potency remains after the removal of act: for a thing is not corrupted into nonbeing, just as neither is a thing generated from absolute non-being. But in intellectual substances, as we have proved,¹ the act is being itself, while the substance is by way of potency. Consequently if an intellectual substance were corrupted, it will remain after its corruption: which is utterly impossible. Therefore, every intellectual substance is incorruptible.

Again. In every thing that is corrupted there must be potency to non-being. Therefore, if there be a thing in which there is not potency to non-being, such a thing is not corruptible. Now there is no potency to non-being in an intellectual substance. For it is clear from what we have said¹ that a complete substance is the proper recipient of being. But the proper recipient of an act is compared as potency to that act in such a way that it is in no way in potency to the opposite: thus fire is compared to heat in such a way that it is in no way in potency to cold. Consequently, neither in corruptible substances is there potency to non-being in the complete substance except by reason of the matter. But there is no matter in intellectual substances, for they are complete simple substances.² Hence there is no potency to non-being in them. Therefore, they are incorruptible.

Moreover. Whatsoever is corrupted, is corrupted either essentially or accidentally. But intellectual substances cannot be corrupted essentially. For all corruption is by a contrary. For an agent, since it acts according as it is an actual being, always brings something into actual being by its action. Consequently, if by this same actual being, something is corrupted through ceasing from actual being, this must result from their mutual contrariety, since contraries are things which exclude one another.¹ Hence whatsoever is corrupted essentially must either have a contrary, or be composed of contraries. But neither of these can be said of intellectual substances. A sign of this is that in the intellect things even of contrary nature cease to be contraries: for white and black are not contraries in the intellect, since they do not exclude one another (in fact, rather do they follow from one another, seeing that by understanding the one we understand the other). Therefore, intellectual substances are not corruptible essentially. Moreover, neither are they corrupted accidentally. For thus accidents and non-subsistent forms are corrupted. Now it was shown above² that intellectual substances are subsistent. Therefore, they are altogether incorruptible.

Further. Corruption is a kind of change: and change must be the term of a movement, as is proved in the Physics.¹ Consequently, whatsoever is corrupted must be moved. Now it was proved in the Physics² that whatsoever is moved is a body. Hence it follows that whatsoever is corrupted is moved—if it be corrupted per se—or else that it is a form or a bodily force dependent on a body, if it be corrupted accidentally. But intellectual substances are neither bodies, nor forces or forms dependent on a body.³ Therefore, they are not corrupted either essentially or accidentally: and consequently they are altogether incorruptible.

Again. Whatsoever is corrupted, is corrupted through being passive to something, since to be corrupted is itself to be passive. Now no intellectual substance can be passive with such a passion as leads to corruption, because to be passive is to be receptive, and that which is received into an intellectual substance must be received according to its mode, namely, intelligibly. Now that which is thus received into an intellectual substance perfects the intellectual substance and does not corrupt it, since the intelligible is the perfection of the intelligent. Therefore, an intelligent substance is incorruptible.

Moreover. The intelligible is the proper perfection of the intellect: hence the intellect in act and the intelligible in act are one.¹ Accordingly, whatever is applicable to the intelligible as such must be applicable to the intellect as such, since perfection and perfectible belong to the one genus. Now the intelligible, as such, is necessary and incorruptible, for necessary things are perfectly knowable by the intellect: whereas contingent things, as such, are only deficiently knowable, because about them we have not science but opinion, so that the intellect has science about corruptibles insofar as they are incorruptible (that is, according as they are universal). Therefore, it follows that the intellect is incorruptible.

Again. A thing is perfected according to the mode of its substance. Consequently, we can gather the mode of a thing’s substance from the mode of its perfection. Now the intellect is not perfected by movement, but by the fact of its being outside movement: for we are perfected by science and prudence as regards the intellective soul, when the movement both of the body and of the soul’s passions are subdued, as the Philosopher states in Physics 7.¹ Hence the mode of an intelligent substance is that its being is superior to movement, and consequently superior to time—whereas the being of every corruptible thing is subject to movement and time. Therefore, it is impossible that an intelligent substance be corruptible.

In both ways, things have a natural desire for being, a sign of which is that not only things devoid of knowledge resist corruptives according to the power of their natural principles, but also those which have knowledge resist the same according to the mode of their knowledge. Consequently, those things lacking knowledge in whose principles there is a power of perpetuating their being (so that they remain ever the same as to individual identity) naturally desire to be perpetuated even in their individual identity: whereas those whose principles contain no such power, but only the power of perpetuating their being in the same species, desire also to be perpetuated in this way.

Hence we must observe this same difference in those things which have a desire of being together with knowledge; namely, so that those who have no knowledge of being except as “now” desire to be as now, but not to be always, because they do not apprehend perpetual being. Yet they desire perpetuity of the species: although without knowledge, because the generative power, which conduces to this effect, is a preamble, and not a subject of knowledge. Therefore, those things which know and apprehend perpetual being desire it with the natural desire. Now this applies to all intelligent substances. Therefore, all intelligent substances, by their natural appetite, desire to be always: consequently, it is impossible that they cease to be.

Further. Whatever things begin to be and cease have both through the same potency, because the same potency regards being and not being. Now intelligent substances could not begin to be except through the potency of the first agent, since they are not made out of matter that could exist before them, as we have proved.¹ Consequently, there is no potency in respect of their not being, except in the first agent insofar as he is able not to pour being into them. But nothing can be said to be corruptible by reason of this potency alone: both because things are said to be necessary and contingent according to a potency that is in them, and not according to God’s potency, as we proved above,² and because God, the author of nature, does not take from things that which is proper to their respective natures. It was shown above that perpetual being is a property of intellectual natures; hence God will not take this from them. Therefore, intellectual substances are in every way incorruptible.

Hence in the Psalm, praise the Lord from the heavens, after mentioning together the angels and heavenly bodies, the text continues: he established them forever and ever (Ps 148:1, 6), thus designating the perpetuity of the aforesaid.

Dionysius also says, in On the Divine Names 4, that on account of the rays of the divine goodness, the intelligible and intellectual substances subsist, are, and live: and their life never fails nor diminishes, for they are free from the universal corruption, knowing neither generation nor death, and they are raised above restless and ever-flowing change.

In what way it is possible for an intellectual substance to be united to the body

Now since it has been shown¹ that an intellectual substance is neither a body, nor a force dependent on a body, it remains for us to inquire whether an intellectual substance can be united to the body.

In the first place, it is clear that an intellectual substance cannot be united to the body by way of a mixture.

For things that are mixed together must be altered in relation to one another. And this does not happen except in those things whose matter is the same, and which can be active and passive in relation to one another.¹ But intellectual substances have no matter in common with corporeal substances, since they are immaterial, as we have proved above.² Therefore, they cannot be mixed with bodies.

Further. Things that are mixed do not remain actually, but only virtually, after the mixture is made: for were they to remain actually it would not be a mixture but only an accumulation; hence a body formed by a mixture of elements is no one of them.¹ But this cannot possibly happen to intellectual substances, since they are incorruptible, as we have proved above.²

Therefore, an intellectual substance cannot be united to the body by way of a mixture.

It is likewise evident that an intellectual substance cannot be united to the body by way of contact, properly so called. For contact is only between bodies, since things are in contact when they come together at their extremes,¹ as the points, lines, or superficies which are the extremes of bodies. Therefore, it is not possible for an intellectual substance to be united to the body by way of contact.

Hence it follows that neither by continuity, nor composition, nor connection is it possible for one thing to result from an intellectual substance with the body. For none of these is possible without contact.

And yet there is a kind of contact by which it is possible for an intellectual substance to be united to a body. For natural bodies are mutually alterative when in contact with one another, so that they are united to one another not only as to their quantitative extremes, but also in like manner to qualities or forms, when an alterative impresses its like on the thing altered. And although, if we consider only the quantitative extremes, there is need in all cases for contact to be mutual, nevertheless if we consider action and passion, we shall find certain things to be only touching, and others only touched, for the heavenly bodies touch the elemental bodies in this way, insofar as they alter them; yet they are not touched by them, since they do not suffer from them. Accordingly, if there be any agents which are not in contact by their quantitative extremes, they will be said nevertheless to touch, insofar as they act, in which sense we say that a person who makes us sorrowful touches us. Therefore, it is possible for an intellectual substance to be united to a body by contact, by touching it in this way. For intellectual substances act on bodies and move them, since they are immaterial and more actual.

This contact, however, is not quantitative, but virtual. Therefore, this contact differs from bodily contact in three ways. First, because by this contact the indivisible can touch the divisible. Now this cannot happen in bodily contact, because nothing but what is indivisible can be touched by a point. But an intellectual substance, although indivisible, can touch a divisible quantity insofar as it acts upon it. For a point is indivisible in one way, and an intellectual substance in another. A point is indivisible as being the term of a quantity; therefore, it has a determined position in a continuous quantity, beyond which it cannot stretch. But an intellectual substance is indivisible as being outside the genus of quantity, so that no quantitative indivisible is assigned with which it can come into contact. Second, because quantitative contact is only in respect of extremes, whereas virtual contact regards the whole thing touched. For it is touched inasmuch as it suffers and is moved. Now this is according as it is in potency: and potency regards the whole and not the extremes of the whole. Therefore, the whole is touched. From this follows the third difference, because in quantitative contact which takes place in regard to the extremes, that which touches must be outside that which is touched, and cannot pierce it, since it is hindered by it. Whereas virtual contact, which applies to intellectual substances, since it reaches inwards, makes the touching substance to be within the thing touched, and to penetrate it without hindrance.

Accordingly, an intellectual substance can be united to a body by virtual contact. Now things united by contact of this kind are not one simply. For they are one in action and passion, which is not to be one simply. For “one” is predicated in the same way as “being.” But to be an agent does not signify being simply. Consequently, neither is to be one in action to be one simply.

Now “one simply” is taken in three ways: either as being indivisible, or as being continuous, or as being logically one. But the one which is indivisible cannot result from an intellectual substance and a body: for the one of this latter kind must be composed of the two. Nor again can the one that is continuous, because the parts of the continuous are parts of quantity. It remains, therefore, for us to inquire whether from an intellectual substance and a body can be formed the one which is one logically.

Now from two things that stay there does not result something logically one except from substantial form and matter, since from subject and accident there does not result one logically, for the idea of “man” is not the same as the idea of “white.” Hence it remains for us to inquire whether an intellectual substance can be the substantial form of a body.

And to those who consider the question reasonably it would seem that this is impossible.¹

For from two actually existing substances there cannot be made something one, because the act of a thing is that by which it is distinguished from another. Now an intellectual substance is an actually existing substance, as is clear from what has been said:¹ and so likewise is a body. Therefore, seemingly, something one cannot be made from an intellectual substance and a body.

Again. Form and matter are contained in the same genus, since every genus is divided into act and potency. But intellectual substance and body are of different genera. Therefore, it does not seem possible that one be the form of the other.

Moreover. Everything whose being is in matter must be material. Now if an intellectual substance is the form of a body, its being must be in corporeal matter, since the being of the form is not beside the being of the matter. Hence it will follow that an intellectual substance is not immaterial, as above it was proved to be.¹

Again. That which has its being in a body cannot possibly be separated from that body. Now it is proved by philosophers that the intellect is separate from the body, and that it is neither a body nor a power in a body. Therefore, an intellectual substance is not the form of a body, for thus its being would be in a body.

Further. That which has its being in common with a body must have its operation in common with a body, because a thing acts inasmuch as it is a being: nor can the active power of a thing surpass its essence, since power results from the essential principles. But if an intellectual substance be the form of a body, its being must be common to it and the body, because from form and matter there results one thing simply, that exists by one being. Consequently, an intellectual substance will have its operation in common with the body, and its power will be a power in a body, which has been proved to be impossible.¹

The opinion of Plato concerning the union of the intellectual soul with the body

Moved by these and like reasons, some have asserted that no intellectual substance can be the form of a body. But since man’s very nature seemed to controvert this opinion, in that he appears to be composed of intellectual soul and body, they devised certain solutions so as to save the nature of man.

Accordingly, Plato and his school held that the intellectual soul is not united to the body as form to matter, but only as mover to movable, for he said that the soul is in the body as a sailor in a boat.¹ In this way, the union of soul and body would only be by virtual contact, of which we have spoken above.²

But this would seem inadmissible. For according to the contact in question, there does not result one thing simply, as we have proved.¹ However, there results a man from the union of soul and body. It follows, then, that a man is not one simply, and neither consequently a being simply, but accidentally.

In order to avoid this, Plato said that a man is not a thing composed of soul and body, but that the soul itself using a body¹ is a man: thus Peter is not a thing composed of man and clothes, but a man using clothes.

But this is shown to be impossible. For animal and man are sensible and natural things. But this would not be the case if the body and its parts were not of the essence of man and animal, and the soul were the whole essence of both, as the aforesaid opinion holds: for the soul is neither a sensible nor a material thing. Consequently, it is impossible for man and animal to be a soul using a body, and not a thing composed of body and soul.

Again. It is impossible that there be one operation of things diverse in being. And in speaking of an operation being one, I refer not to that in which the action terminates, but to the manner in which it proceeds from the agent: for many persons rowing one boat make one action on the part of the thing done, which is one, but on the part of the rowers there are many actions, for there are many strokes of the oar. For it follows that things differing in forms and powers differ in action, since action is consequent upon form and power. Now, though the soul has a proper operation in which the body has no share (namely, intelligence), there are nevertheless certain operations common to it and the body, such as fear, anger, sensation, and so forth; for these happen by reason of a certain transmutation in a determinate part of the body, which proves that they are operations of the soul and body together. Therefore, from the soul and body there must result one thing, and they have not each a distinct being.

According to the opinion of Plato, this argument may be rebutted. For it is not impossible for mover and moved, though different in being, to have the same act, because the same act belongs to the mover as that from which it is, and to the moved as that in which it is.¹ Therefore, Plato held that the aforesaid operations are common to the soul and body, namely, so that they are the soul’s as mover and the body’s as moved.

But this cannot be. For as the Philosopher proves in On the Soul 2: sensation results from our being moved by exterior sensibles.¹ Therefore, a man cannot sense without an exterior sensible, just as a thing cannot be moved without a mover. Consequently, the organ of sense is moved and passive in sensing, but this is owing to the external sensible. And that by which it is passive is the sense, which is proved by the fact that things devoid of sense are not passive to sensibles by the same kind of passion. Therefore, sense is the passive power of the organ. Consequently, the sensitive soul is not as mover and agent in sensing, but as that by which the patient is passive. And this cannot have a distinct being from the patient. Therefore, the sensitive soul has not a distinct being from the animate body.

Moreover. The movable does not derive its species from its mover. Consequently, if the soul is not united to the body except as mover to movable, the body and its parts do not take their species from the soul. Therefore, at the soul’s departure, the body and its parts will remain of the same species. Yet this is clearly false: for flesh, bone, hands, and like parts are so called only equivocally after the soul’s departure,¹ since none of these parts retains its proper operation that results from the species. Therefore, the soul is not united to the body merely as mover to movable, or as man to his clothes.

Further. The movable does not have being through its mover, but only movement. Consequently, if the soul be united to the body merely as its mover, the body will indeed be moved by the soul, but will not have being through it. But in the living thing to live is to be.¹ Therefore, the body would not live through the soul.

Again. The movable is neither generated through the mover’s application to it nor corrupted by being separated from it, since the movable depends not on the mover for its being, but only in the point of being moved. If, then, the soul be united to the body merely as its mover, it will follow that neither in the union of soul and body will there be generation, nor corruption in their separation. And thus death, which consists in the separation of soul and body, will not be the corruption of an animal, which is clearly false.

That the soul is united to the body as its proper form is proved thus. That by which a thing, from being potentially, is made an actual being, is its form and act. Now the body is made by the soul an actual being from existing potentially, since to live is the being of a living thing.¹ But the seed before animation is only a living thing in potency, and is made an actually living thing by the soul. Therefore, the soul is the form of the animated body.

Moreover. Since both being and operation belong neither to the form alone, nor to the matter alone, but to the composite, being and action are ascribed to two things, one of which is to the other as form to matter; for we say that a man is healthy in body and in health, and that he is knowing in knowledge and in his soul, in which knowledge is a form of the soul knowing, and health of the healthy body. Now “to live” and “to sense” are ascribed to both soul and body, for we are said to live and sense both in soul and body, but by the soul as by the principle of life and sensation. Therefore, the soul is the form of the body.

Further. The whole sensitive soul has to the whole body the same relation as part to part. Now part is to part in such a way that it is its form and act, for sight is the form and act of the eye. Therefore, the soul is the form and act of the body.

That the nutritive, sensitive, and intellective faculties in man are not three souls

But the foregoing arguments,¹ according to the opinion of Plato, can be answered so far as it pertains to the present concern. For Plato² holds that in us the same soul is not intellective, nutritive, and sensitive. Hence, even if the sensitive soul were the form of the body, we should not have to conclude that an intellectual substance can be the form of a body.

That this opinion is impossible, we must show as follows.

Things that are ascribed to one and the same thing according to various forms are predicated of one another accidentally: for a white thing is said to be musical accidentally, because whiteness and music are ascribed to Socrates. Consequently, if the intellective, sensitive, and nutritive soul are various forces or forms in us, those things which are ascribed to us in respect of these forms will be predicated of one another accidentally. Now in respect of the intellective soul we are said to be men; according to the sensitive soul, animals; according to the nutritive soul, living. Therefore, this predication “man is an animal,” or “an animal is a living thing,” will be accidental. But it is an essential¹ predication, since man, as man, is an animal, and animal, as animal, is a living thing. Therefore, it is from the same principle that one is a man, an animal, and a living thing.

If, however, it be said that, even if the aforesaid souls be distinct, it does not follow that the predication mentioned will be accidental, because these souls are mutually subordinate: we reply to this also. For the sensitive power is subordinate to the intellect, and the nutritive power to the sensitive, as potency is subordinate to act: for the intellect comes after the sensitive, and the sensitive after the nutritive in the order of generation, since in generation an animal is made before a man.

Consequently, if this order makes the aforesaid predications to be essentially, this will not be taking “essential” in the sense that arises from the form, but in that which arises from matter and subject, as a surface is said to be colored.¹ But this is impossible, because when we use “essential” in this sense, that which is formal is predicated essentially of the subject, as when we say: “the surface is white” or “the number is even.” Again, when we use “essential” in this way, the subject is placed in the definition of the predicate, as number in the definition of “even.” But here the contrary happens, because man is not predicated of animal essentially, but contrariwise. Again, the subject is not placed in the definition of the predicate, but vice versa. Therefore, the aforesaid definitions are not said essentially by reason of the order in question.

Again. The aforesaid¹ difficulty will again arise, namely, that from the intellective soul and the body there results one thing not simply, but only accidentally. For whatever accrues to a thing after its complete being accrues to it accidentally, since it is outside its essence. Now every substantial form makes a complete being in the genus of substance, for it makes an actual being and this particular thing. Consequently, whatever accrues to a thing after its first substantial form will accrue to it accidentally. Hence, since the nutritive soul is a substantial form—for “living” is predicated substantially of man and animal—it will follow that the sensitive soul accrues accidentally, and likewise the intellective. And so neither “animal” nor “man” denotes one thing simply, nor a genus or species in the category of substance.

Moreover. If man, in Plato’s opinion, is not a thing composed of body and soul, but a soul using a body,¹ this is to be understood either of the intellective soul only, or of the three souls, if there be three, or of two of them. If of three or two, it follows that man is not one thing, but two or three, for he is three souls (or at least two). And if this be only understood of the intellective soul (so that the sensitive soul be understood to be the body’s form, and the intellective soul, using the animated and sensified body, to be a man), this would again involve absurdities, namely, that man is not an animal, but uses an animal, and that man does not sense, but uses a sentient thing. And since these statements are inadmissible, it is impossible that there be in us three souls differing in substance: the intellective, the sensitive, and the nutritive.

Further. One thing cannot be made of two or three without something to unite them, unless one of them be to the other as act to potency: for thus are matter and form made one thing without anything outside uniting them. Now if there be several souls in man, they are not mutually related as matter and form, but are only supposed to be acts and principles of action. Consequently, it follows that there is something to unite them if they be united to form one thing (for instance, a man or an animal). But this cannot be the body, since the body is rather united together by the soul—a sign of which is that when the soul departs, the body perishes. It results, then, that there must be something more formal to make these several things into one. And this will be the soul, rather than those several that are united by this thing. Therefore, if this again has various parts, and is not one thing in itself, there will still be need of something to unite them. Since, then, we cannot go on indefinitely, we must come to something that is one in itself. And such especially is the soul. Therefore, there must be but one soul in one man or in one animal.

Again. If that which belongs to the department of the soul in man is composed of several things, it follows that as the whole together is to the whole body, so each of them is to each part of the body. Nor does this disagree with Plato’s opinion: for he placed the rational soul in the brain, the nutritive in the liver, and the appetite in the heart.¹ But this is shown to be false, for two reasons. First, because there is a part of the soul which cannot be ascribed to any part of the body—namely, the intellect, of which it has been proved² that it is not the act of any part of the body. Second, because it is evident that the operations of different parts of the soul are observed in the same part of the body: as is clear in animals which live after being cut in two, since the same part has the movement, sensation, and appetite by which it is moved; and likewise the same part of a plant, after being cut off, is nourished, grows and blossoms. Hence it is evident that the various parts of the soul are in the one and same part of the body. Therefore, there are not different souls in us, allotted to different parts of the body.

Moreover. Different forces that are not rooted in one principle do not hinder one another in acting, unless perhaps their action be contrary, which does not happen in the case in point. Now we find that the various actions of the soul hinder one another, since when one is intense, another is remiss. It follows, then, that these actions, and the forces that are their proximate principles, must be reduced to one principle. But this principle cannot be the body, both because there is an action in which the body has no part (namely, intelligence), and because if the body as such were the principle of these forces and actions, they would be found in all bodies, which is clearly false. Consequently, it follows that their principle is some one form, by which this body is such a body: and this is the soul. Therefore, it follows that all the soul’s actions which are in us proceed from one soul. Therefore, there are not several souls in us.

This is in agreement with what is said in the book De Ecclesiasticis dogmatibus, 15: Nor do we say that there are two souls in one man, as James and other Syrians write: one, animal, by which the body is animated, and which is mingled with the blood; the other, spiritual, which supplies the reason. But we say that it is one and the same soul in man that both gives life to the body by being united to it, and orders itself by its own reason.

That man’s possible intellect is not a separate substance

There have been others who discovered another reason for maintaining that the intellectual soul cannot be united to the body as its form. For they say that the intellect which Aristotle calls possible¹ is a separate substance, not united to us as a form.

They endeavor to prove this from the words of Aristotle, who says, speaking of this intellect, that it is separate, not mixed with the body, simple, and impassible¹—which, if it were the body’s form, could not be said of it.

Also, from the demonstration by which he proves¹ that, since the possible intellect receives all the species of sensible things through being in potency to them, it must lack them all. Even so the pupil, which receives the species of all colors, lacks all color; for if it had any color by itself, that color would prevent it seeing other colors; in fact it would see nothing but under that color. The same would happen with the possible intellect, if by itself it had any form or nature of sensible things. Yet it would have to be so if it were bound up with the body. Likewise if it were the form of a body, because, since one thing is made from form and matter, the form must participate in something of the nature of which it is the form. Consequently, it is impossible that the possible intellect be bound up with the body, or be the act or form of a body.

Further. If it were the form of a material body, the receptivity of such an intellect would be of the same kind as the receptivity of prime matter, because that which is the form of a body receives nothing without its matter. Now prime matter receives individual forms: in fact, they are individualized through being in matter. Therefore, the possible intellect would receive forms as they are individual: and consequently would not be cognizant of universals, which is clearly false.

Moreover. There cannot possibly be an infinite power in a body, as proved by Aristotle in Physics 8.¹ Now the possible intellect is, in a manner, of infinite power, since by it we judge of an infinite number of things insofar as by it we know universals, under which potentially infinite particulars are contained. Therefore, the possible intellect is not a power in a body.

For these reasons Averroes¹ was moved, and likewise some of the ancients, as he says, to hold that the possible intellect, by which the soul understands, has a separate being from the body, and is not the form of the body.

Since, however, such an intellect would in no way belong to us, nor would we understand by it unless it were in some way united to us, he defines the way in which it comes into touch with us,¹ saying that the species actually understood is the form of the possible intellect, just as the actually visible is the form of the visual power. Hence there results one thing from the possible intellect and the actually understood form. Consequently, the possible intellect is united to whomever the aforesaid understood form is united. Now it is united to us by means of the phantasm, which is a kind of subject of that understood form: and in this way the possible intellect also is in touch with us.

But it is easy to see that all this is nonsensical and impossible. For the one who understands is the one who has intellect. And the thing understood is the thing whose intelligible species is united to the intellect. Consequently, though the intelligible species united to the intellect is in a man in some way, it does not follow that the man is the one who understands, but only that he is understood by the separate intellect.

Again. Every knower by its cognitive power is united to its object, and not vice versa, just as every operator by its operative power is united to the thing operated. Now man is intelligent by his intellect as by his cognitive power. Therefore, he is not united to the intellect by the intelligible form, but by the intellect he is united to the intelligible.

Moreover. That by which a thing operates must be its form, for nothing acts except insofar as it is in act, and a thing is not in act except by that which is its form: hence Aristotle proves that the soul is a form from the fact that an animal lives and senses through the soul.¹ Now man understands, and this by his intellect only: thus Aristotle, when inquiring into the principle whereby we understand, describes to us the nature of the possible intellect.² Therefore, the possible intellect must be united to us formally and not merely by its object.

Now it is evident that he who devised this opinion was deceived by an equivocation. For colors existing outside the soul, given the presence of light, are actually visible as being able to move the sight, and not as actually perceived, according as they are one with the sense in act. In like manner, the phantasms are made actually intelligible by the light of the active intellect, so that they can move the possible intellect, but not so that they be actually understood, according as they are one with the possible intellect made actual.

Again. Where the living thing has a higher operation, there is a higher kind of life corresponding to that operation. For in plants we find only an action pertaining to nutrition. In animals we find a higher operation, namely sensation and local movement: and hence the animal lives by a higher kind of life. But in man we find a yet higher vital operation than in the animal, namely intelligence. Therefore, man must have a higher kind of life. Now life is through the soul. Therefore, man will have a higher soul by which he lives, than is the sensitive soul. But none is higher than the intellect. Therefore, the intellect is man’s soul, and consequently it is his form.¹

Further. That which is consequent on the operation of a thing does not give a thing its species, because operation is a second act, whereas the form by which a thing has species is the first act. Now the union of the possible intellect with man, according to the above opinion, is consequent on man’s operation: for it takes place through the medium of the phantasm which, according to the Philosopher,¹ is a movement resulting from the sense in act. Therefore, man does not take his species from that union, and consequently man differs from dumb animals by the fact that he has an intellect.

Moreover. If man takes his species from being rational and having an intellect, whoever is in the human species is rational and intelligent. But a child, even before leaving the womb, is in the human species: and yet it does not have phantasms that are actually intelligible. Therefore, a man does not have an intellect through the intellect being in contact with man by means of an intelligible species, the subject of which is a phantasm.

That man derives his species not from the passive, but from the possible intellect

To these arguments there is a reply on the lines of the foregoing opinion.¹ For the aforesaid Averroes² maintains that man differs in species from brutes by the intellect which Aristotle calls passive, which is the same as the cogitative power that is proper to man, in place of which other animals have a certain natural estimative power. And it belongs to this cogitative power to distinguish individual intentions and to compare them with one another, just as the intellect, which is separate and unmixed, compares and distinguishes universal intentions. And since by this power, together with the imagination and memory, the phantasms are prepared to receive the addition of the active intellect, by which they are made actually intelligible—just as certain arts prepare the matter for the master craftsman—therefore, the aforesaid power is called by the name of intellect or reason, which physicians declare to be seated in the middle cell of the head. And according to the disposition of this power, one man differs from another in genius and other points pertaining to intelligence. Also, by the use and practice of it, man acquires the habit of science: so that the habits of science are in this passive intellect as their subject. Moreover, this passive intellect is in the child from the beginning, and through it the child receives its human species before understanding actually.

But it is easy to see that all this is untrue and an abuse of terms. For vital operations are compared to the soul as second acts to the first, as Aristotle declares in On the Soul 2.¹ Now in the one subject, first act precedes the second in point of time, just as knowledge precedes consideration. Hence in whatever thing we find a vital operation, we must place some part of the soul that will be compared to that operation as first to second act. Now man above other animals has a proper operation, namely, intelligence and reasoning, which is the operation of man as man, as Aristotle states.² Therefore, we must place in man a principle that properly gives him his species, and is compared to the act of intelligence as first to second act. But this cannot be the aforesaid passive intellect, since the principle of this same operation must be impassible and not mixed with the body, as the Philosopher proves,³ whereas it is clearly the contrary with the passive intellect. Therefore, it is not possible that the species by which man differs from other animals should come to him through the cogitative power that is called the passive intellect.

Again. That which is a passion of the sensitive part cannot place a thing in a higher kind of life than the sensitive life, just as that which is a passion of the nutritive soul does not place a thing in a higher kind of life than the nutritive. Now it is clear that the imagination and the like powers which are consequent upon it (such as the memory and so forth), are passions of the sensitive faculty, as the Philosopher proves in his book On Memory.¹ Consequently, an animal cannot be placed by these powers, or by any one of them, in a higher kind of life than the sensitive. But man is in a higher kind of life, as is proved from the Philosopher in On the Soul 2,² who, in distinguishing the kinds of life, places the intellective, which he ascribes to man, above the sensitive, which he ascribes to all animals in common. Therefore, it is not through the aforesaid cogitative power that man is a living being, with a life proper to himself.

Moreover. Every self-mover, as the Philosopher proves in Physics 8,¹ is composed of mover and moved. Now man, like the animals, is a self-mover. Therefore, mover and moved are parts of him. But the first mover in man is the intellect, for the intellect by its intelligible object moves the will. Nor can it be said that the passive intellect alone is the mover, since the passive intellect is only of particulars, while in moving there comes into play both the universal opinion which belongs to the possible intellect, and the particular statement which may belong to the passive intellect, as we gather from Aristotle.² Therefore, the possible intellect is a part of man and is the most noble and most formal thing in him. Consequently, he takes his species from it, and not from the passive intellect.

Further. The possible intellect is proved not to be the act of a body from the fact of its taking cognizance of all sensible forms in the universal.¹ Therefore, no power, the operation of which can extend to the universals of all sensible forms, can be the act of a body. Now such is the will, since our will can extend to all the things that we can understand, at least so that we will to know them. Moreover, the act of the will is clearly directed to the universal: for we hate, as Aristotle says in his Rhetoric, the robber-kind in the universal, but are enraged only with the individuals.² Consequently, the will cannot be the act of a part of the body, nor can it be consequent upon a power that is an act of the body. Now any part of the soul is an act of the body, except the intellect alone properly so called. Hence the will is in the intellective part; hence also Aristotle says that the will is in the reason, but the irascible and concupiscible are in the sensitive part.³ On account of this, the acts of the concupiscible and irascible are associated with passion; but the act of the will is not associated with passion, but with choice. Now man’s will is not outside man, as though it were vested in a separate substance, but is in man himself. Else he would not be master of his own actions, for he would be acted upon by the will of a separate substance: and in him there would only be the appetitive powers that operate with passion—namely, the irascible and the concupiscible, which are in the sensitive part, as in other animals which are acted upon rather than act themselves. But this is impossible, and would do away with all moral philosophy and political life. Therefore, the possible intellect must be in us so that we differ thereby from dumb animals, and not only by the passive intellect.

Again. Just as nothing is powerful to act except through an inherent active power (or potency), so nothing is able to be passive except through an inherent passive potency: for the combustible is not only able to be burnt because there is something able to burn it, but also because it has in itself a potency to be burnt. Now to understand is a kind of passion, as stated in On the Soul 3.¹ Since, then, a child is potentially understanding, although he does not understand actually, there must be in him a potency by which he is able to understand: and this potency is the possible intellect. Consequently, the possible intellect must already be in touch with the child before he understands actually. Therefore, the contact of the possible intellect with man is not through the actually understood form, but the possible intellect itself is in a man from the beginning as a part of him.

The said Averroes replies to this argument.¹ For he says that a child is said to be potentially understanding in two ways. First, because the phantasms in him are potentially intelligible; second, because the possible intellect is able (potens) to come in touch with him, and not because the intellect is already united to him.

Now we have to prove that either way is insufficient. For the potency by which the agent is able to act is distinct from the potency whereby the patient is able to be passive, and they differ as being opposite to one another. Consequently, from the fact that a thing is able to be active, it is not competent to it to be passive. Now to be able to understand is to be able to be passive, since to understand is a kind of passion, according to the Philosopher.¹ Therefore, the child is not said to be able to understand from the mere fact that the phantasms in him are able to be actually understood, since this pertains to being able to act, for the phantasms move the possible intellect.

Again. A potency consequent on the species of a thing does not belong to it by reason of that which does not give that thing its species. Now ability to understand is consequent on the human species, for understanding is an operation of man as such. The phantasms do not give man his species; on the contrary, they are consequent on his operation. Therefore, the child cannot be said to be potentially understanding by reason of the phantasms.

Likewise, neither can a child be said to be potentially understanding, because the possible intellect is able to be in touch with him. For a person is said to be able to act or to be passive by active or passive potency, just as he is said to be white by whiteness. Now he is not said to be white before whiteness is united to him. Therefore, neither is one said to be able to act or to be passive before the active or passive potency is in him. Consequently, it cannot be said of a child that he is able to understand before the possible intellect, which is the power of understanding, is in touch with him.

Again. A habit is that by which one acts at will.¹ Consequently, a habit must be in the same subject as the operation that is according to that habit. But to consider by understanding, which is the act of the habit of science, cannot be in the passive intellect, but belongs to the possible intellect; because in order that a power understand, it must not be the act of a body. Therefore, the habit of science is not in the passive, but in the possible intellect. Now science is in us, since according to it we are said to know scientifically. Therefore, the possible intellect also is in us, and does not have a being separate from us.

Further. The assimilation of science is of the knower to the thing known. Now the knower is not assimilated to the thing known, as such, except in respect of universal species, for science is about such things. But universal species cannot be in the passive intellect—since it is a power using an organ—but only in the possible intellect. Therefore, science is not in the passive, but only in the possible intellect.

Moreover. The intellect in habit, as the opponent admits,¹ is the effect of the active intellect. Now the effects of the active intellect are things actually intelligible, whose proper recipient is the possible intellect (to which the active intellect is compared as art to material, according to Aristotle).² Consequently, the intellect in habit, which is the habit of science, must be in the possible, and not in the passive intellect.

Again. Whatever things are separate as to being are also separate as to operation, because things are for the sake of their operations, as first act for the sake of the second. Hence Aristotle says that if any operation of the soul is apart from the body, it is possible for the soul to be separated.¹ Now the operation of the possible intellect requires the body: for the Philosopher says, in On the Soul 3,² that the intellect can act by itself (that is, it can understand) when it has been made actual by a species abstracted from phantasms, which are not apart from the body. Therefore, the possible intellect is not altogether separate from the body.

Moreover. A thing has those attributes by nature without which its connatural operation cannot be accomplished: thus Aristotle proves, in On the Heavens 2,¹ that if the movement of the stars were progressive like that of animals, nature would have given them the organs of progressive movement. Now the operation of the possible intellect is accomplished through corporeal organs, which are necessary as subjects of the phantasms. Therefore, nature has united the possible intellect to corporeal organs: consequently, it does not have a being separate from the body.

Again. If it had a being separate from the body, it would understand substances that are separate from matter rather than sensible forms, for they are more intelligible and more conformed to the intellect. Yet it cannot understand substances that are altogether separate from matter, since there are no phantasms of them: whereas this intellect in no way understands without phantasms, as Aristotle says in On the Soul 3.¹ For the phantasms are to it as sensibles to the senses, and without these the sense has no sensation. Therefore, it is not a substance separate from the body in being.

Further. In every genus the passive potency extends as far as the active potency of that genus; therefore, there is not a passive potency in nature to which there does not correspond a natural active potency. But the active intellect makes only the phantasms to be intelligible. Therefore, neither is the passive intellect moved by other intelligibles than the species abstracted from the phantasms: and thus it is unable to understand separate substances.

Moreover. The species of sensible things are in separate substances intelligibly, and by those species they have knowledge of sensibles. If, therefore, the possible intellect understood separate substances, it would receive in them the knowledge of sensibles. Consequently, it would not receive this knowledge from phantasms, since nature’s abundance does not consist of superfluities.

If, however, it be said that separate substances have no knowledge of sensibles, it must at least be granted that they have a higher knowledge. And this knowledge must not be lacking to the possible intellect, if it understands the said substances. Consequently, it will have a twofold knowledge—one after the manner of separate substances, the other received from the senses—one of which would be superfluous.

But these are responded to by the aforesaid opinion.¹ The possible intellect, so far as it is self-subsistent, understands separate substances, and is in potency to them as a transparent body to the light. But insofar as it is in touch with us, it is in potency from the beginning to forms abstracted from the phantasms. Hence we do not from the beginning understand separate substances by it.

But this will not hold. For the possible intellect, according to them, is said to be in touch with us through being perfected by intelligible species abstracted from the phantasms. Consequently, the intellect is to be considered as in potency to these species before being in touch with us. Therefore, it is not by its being in touch with us that it is in potency to these species.

Further. It is impossible for the possible intellect to understand several things at the same time, unless it understand one through another, since one power is not perfected at the same time by several acts except according to order. If, therefore, the possible intellect understands separate substances, and species abstracted from phantasms, it must either understand separate substances through these species, or vice versa. Now whichever be granted, it follows that we understand separate substances. For if we understand the natures of sensibles insofar as the possible intellect understands them, and the possible intellect understands them through understanding separate substances, we must understand them in the same way. And in like manner if the case be the reverse. But this is clearly false. Therefore, the possible intellect does not understand separate substances: consequently, it is not a separate substance.

That the aforesaid opinion is contrary to that of Aristotle

Since, however, Averroes endeavors to strengthen his position by appealing to authority, and says¹ that Aristotle was of the same opinion, we shall prove clearly that the aforesaid opinion is contrary to that of Aristotle.

First, because Aristotle in On the Soul 2 defines the soul by saying that the soul is the first act of an organic physical body having life potentially,¹ and afterwards he adds² that this definition applies universally to every soul, not, as the aforesaid Averroes pretends,³ expressing a doubt on the point, as evidenced by the Greek text and the translation of Boethius.

Afterwards, in the same chapter, he adds that certain parts of the soul are separable.¹ Now these are no other than the intellective parts. It follows, therefore, that these parts are acts of the body.

Nor is this gainsaid by what he says afterwards: nothing so far is clear about the intellect and the power of understanding, but it would seem to be another kind of soul.¹ For he does not wish by this to except the intellect from the common definition of a soul, but to exclude it from the natures proper to the other parts: thus he who says “animals that fly are of another kind from those that walk” does not remove the common definition of animal from those that fly. Therefore, to show in what sense he said another, he adds: and this alone can be separated as the everlasting from the corruptible. Nor is it Aristotle’s intention, as the aforesaid Commentator pretends,² to say that he has not yet made it clear concerning the intellect, whether the intellect be the soul, as he had done concerning the other principles.

For the genuine text does not read, nothing has been declared, or nothing has been said, but nothing is clear, which we must understand as referring to that which is proper to the soul, and not as referring to the common definition. And if, as he says,¹ “soul” is said equivocally of the intellect and other souls, he (Aristotle) would first have explained the equivocation, and given the definition afterwards, as is his custom. Otherwise, he would have proceeded under an equivocation; which is not allowable in demonstrative sciences.

Again. In On the Soul 2¹ he reckons the intellect among the powers of the soul, and in the passage quoted he calls it the power of understanding. Therefore, the intellect is not outside the human soul, but is one of its powers.

Again. In the On the Soul 3, when he begins to speak of the possible intellect, he calls it a part of the soul, for the text reads: of the part of the soul whereby the soul has knowledge and wisdom:¹ thus clearly indicating that the possible intellect is a part of the soul.

He is yet more explicit when he goes on to declare the nature of the possible intellect, in these words: by the intellect I mean that by which the soul knows and understands.¹ This evidently denotes that the intellect is a part of the human soul, whereby the soul understands.

Therefore, the aforesaid position is contrary to the opinion of Aristotle, and to the truth. Consequently, it is to be rejected as a mere fabrication.

Against the opinion of Alexander about the possible intellect

Having taken these sayings of Aristotle into consideration, Alexander asserted that the possible intellect is a power in us,¹ so that the common definition of a soul given by Aristotle in On the Soul 2² might apply to it. But as he could not understand how an intellectual substance could be the form of a body, he said that the aforesaid power is not rooted in an intellectual substance, and that it is consequent on the mixture of the elements in the human body. For the particular mode of mixture in the human body makes man to be in potency to receive the inflow of the active intellect, which is always in act, and according to him is a separate substance, the result of which inflow is that man is made to understand actually. Now in man that by which he is potentially understanding is the possible intellect. Consequently, it seemed to follow that the possible intellect in us is a result of a particular mixture.

But at the first glance this opinion is seen to be in contradiction with both the words and the proof of Aristotle. For as already stated¹ Aristotle proves in On the Soul 3 that the possible intellect is not mixed with the body.² Now this could not be said of a power resulting from the mixture of the elements: for a thing of the kind must be rooted in the mixture itself of the elements, as we see in the case of taste, smell, and the like. Therefore, seemingly the aforesaid opinion of Alexander is inconsistent with the words and proof of Aristotle.

To this Alexander replies that the possible intellect is merely the preparedness in the human nature to receive the inflow of the active intellect. And preparedness is not a particular sensible nature, nor is it mixed with the body: for it is a relation and the order of one thing to another.

But this clearly disagrees with the intention of Aristotle. For Aristotle proves that the reason why the possible intellect is not confined to any particular sensible nature, and consequently is not mixed with the body, is because it is receptive of all the forms of sensibles, and cognizant of them. Now this cannot be understood of preparedness, for it denotes not receiving but being prepared to receive. Therefore, Aristotle’s proof refers not to preparedness, but to a prepared recipient.

Moreover. If what Aristotle says of the possible intellect applies to it inasmuch as it is a preparedness, and not on account of the nature of the subject prepared, it follows that it applies to every preparedness. Now in the senses there is a preparedness to receive sensibles actually. Therefore, the same applies to the senses as to the possible intellect. And yet Aristotle clearly says the contrary, when he shows the difference between the receptivity of sense and of intellect, from the fact that sense is corrupted by the excellence of its objects, but not the intellect.

Again. Aristotle says of the possible intellect that it is passive to the intelligible, that it receives intelligible species, that it is in potency to them. He also compares it to a tablet on which nothing is written. None of which things can be said of preparedness, but only of the subject prepared. It is, therefore, contrary to the intention of Aristotle that the possible intellect should be the same as preparedness.

Again. The agent is more noble than the patient, and the maker than the thing made,¹ as act in comparison with potency. Now the more immaterial a thing is, the more noble it is. Therefore, the effect cannot be more immaterial than the cause. But every cognitive power, as such, is immaterial: hence Aristotle says in On the Soul 2 of sense that it is receptive of sensible species without matter.² Consequently, it is impossible for a cognitive power to result from a mixture of elements. Now the possible intellect is the highest cognitive power in us: for Aristotle says in On the Soul 3 that the possible intellect is whereby the soul knows and understands.³ Therefore, the possible intellect is not caused by the mixture of the elements.

Moreover. If the principle of an operation proceeds from certain causes, that operation must not surpass those causes, since the second cause acts by virtue of the first. Now even the operation of the nutritive soul exceeds the power of the elemental qualities: for Aristotle proves in On the Soul 2 that fire is not the cause of growth, but its concause so to speak, while its principal cause is the soul,¹ to which heat is compared as the instrument to the craftsman. Consequently, the vegetative soul cannot be produced by the mixture of the elements, and much less, therefore, the sense and possible intellect.

Again. To understand is an operation in which no bodily organ can possibly communicate. Now this operation is ascribed to the soul, as also to man, for we say that the soul, or man by his soul, understands. Consequently, there must be in man a principle, independent of the body, which is the source of that operation. But the preparedness that results from the mixture of the elements is clearly dependent on the body. Therefore, preparedness is not this principle. And yet this latter is the possible intellect, since Aristotle says in On the Soul 3¹ that the possible intellect is whereby the soul knows and understands. Therefore, preparedness is not the possible intellect.

If, however, it be said that the principle of the aforesaid operation in us is the intelligible species made actual by the active intellect: this is seemingly insufficient. For, since man from being intentionally understanding is made actually understanding, it follows that not only does he understand by the intelligible species, by which he is made to understand actually, but also by an intellective power, which is the principle of the aforesaid operation, as happens also with the senses. Now Aristotle affirms that this power is the possible intellect. Therefore, the possible intellect is independent of the body.

Again. The possible intellect is described by Aristotle as being part of the soul.¹ Now the soul is not a preparedness, but an act, since preparedness is the order of potency to act. And yet act is followed by a certain preparedness to a further act: for instance, the act of transparency is followed by an order to the act of light. Therefore, the possible intellect is not a mere preparedness, but is an act.

Moreover. Man obtains species and human nature according to that part of the soul which is proper to him, namely, the possible intellect.¹ Now nothing obtains species and nature according as it is in potency, but according as it is in act. Since, then, preparedness is nothing more than order of potency to act, it is impossible that the possible intellect be merely a certain preparedness in human nature.

That the soul is not a temperament, as Galen asserted

The opinion of the physician Galen about the soul is akin to the aforesaid opinion of Alexander concerning the possible intellect. For he says that the soul is a temperament.¹ He was moved to make this assertion by the fact that we see various passions which are ascribed to the soul resulting from various temperaments in us: for some who have, for example, a choleric temperament, are easily angered, while melancholic persons are prone to be sad. Consequently, the same arguments avail to disprove this opinion, as were adduced against the opinion of Alexander,² as well as some that apply properly to it.

For it was proved above¹ that the operation of the vegetative soul, sensitive knowledge and (much more) the operation of the intellect surpass the power of the active and passive qualities. Therefore, the temperament cannot be the principle of the soul’s operations. Consequently, it is impossible for the soul to be the temperament.

Again. Seeing that the temperament is something set up by contrary qualities as a kind of mean between them, it cannot possibly be a substantial form, because substance has no contrary, nor is it a recipient of more or less.¹ But the soul is a substantial, not an accidental, form, or else a thing would not obtain species or form from its soul. Therefore, the soul is not the temperament.

Further. The temperament does not move an animal’s body by local movement: for it would follow the movement of the predominant element, and thus would always be moved downwards. But the soul moves the body in all directions. Therefore, the soul is not the temperament.

Moreover. The soul rules the body, and curbs the passions that result from the temperament. For by temperament some are more prone than others to desire or anger, and yet refrain more from these things, on account of something that keeps them in check, as may be seen in those who are continent. But the temperament does not this. Therefore, the soul is not the temperament.

Apparently he was deceived through failing to observe that passions are ascribed to the temperament in one way, and to the soul in another. For they are ascribed to the temperament as causing a disposition, and in respect of that which is material in the passions—for instance, the heat of the blood and the like—while they are ascribed to the soul as their principal cause, and in respect of what is formal in the passions—for instance, the desire of vengeance in anger.

That the soul is not a harmony

Not unlike the foregoing opinion is the view of those who say that the soul is a harmony. For they meant that the soul is a harmony not of sound, but of contraries, of which they observed animate bodies to be composed. In the On the Soul¹ this opinion is apparently set down to Empedocles; Gregory of Nyssa² ascribes it to Dinarchus; and it is to be refuted in the same way as the foregoing opinion, as well as by arguments proper to itself.

For every mixed body has harmony and temperament. Nor can harmony move a body, nor rule it, nor curb the passions, any more than temperament can do so. Again, it is subject to intension and remission, like temperament. All of which show that the soul is neither harmony nor temperament.

Again. The notion of harmony applies more to the qualities of the body than to those of the soul: for health is harmony of the humors; strength, of sinews and bones; beauty, of limbs and colors. But it cannot be said of what things sense or intellect or other parts of the soul are the harmony. Therefore, the soul is not a harmony.

Moreover. Harmony is taken in two senses. In one way, for the composition itself, in another for the manner of composition. Now the soul is not a composition, because each part of the soul would have to be the composition of some of the parts of the body, and this cannot be assigned. Likewise, it is not the manner of a composition: because, since in the various parts of the body there are various manners or proportions of composition, each part of the body would have a distinct soul—for bone, flesh, and sinew would have different souls, since they are composed in different proportions—which is clearly false. Therefore, the soul is not a harmony.

That the soul is not a body

There were also others who wandered further from the truth by asserting that the soul is a body. And although these had different and various opinions, it will suffice to refute them here in general.

For living things, since they are physical beings, are composed of matter and form. Now they are composed of a body, and of a soul which makes them actually living. Therefore, one of these must be the form, and the other the matter. But the body cannot be the form, since the body is not in something else as its matter and subject. Therefore, the soul is the form. Consequently, it is not a body, since no form is a body.

Again. It is impossible for two bodies to coincide. Now the soul is not apart from the body while the latter lives. Therefore, the soul is not a body.

Moreover. Every body is divisible. And whatever is divisible requires something to keep together and unite its parts. Consequently, if the soul were a body, it would have something else to hold it together, and this yet more would be the soul, since we observe that when the soul departs, the body perishes. And if this again be divisible, we must at length either come to something indivisible and incorporeal, which will be the soul, or we shall go on to infinity, which is impossible. Therefore, the soul is not a body.

Again. As we proved above (Bk. 1, ch. 13), and as it is proved in Physics 8,¹ every self mover is composed of two parts, of which the one is mover, the other moved. Now an animal is a self-mover, and the mover in it is the soul, while the body is moved. Consequently, the soul is an unmoved mover. But no body moves without being moved, as we proved above.² Consequently, the soul is not a body.

As to the arguments by which some have tried to prove that the soul is a body, it is easy to solve them. For they prove that the soul is a body from the son being like his father even in the accidents of the soul, notwithstanding that the son is begotten of his father by bodily detachment. Also because the soul suffers with the body. Also because it is separate from the body, and separation is between bodies that touch one another.

Moreover, many men were moved to take up this position through believing that there is nothing that is not a body, being unable to transcend their imagination which is only about bodies.

Hence this opinion is put forward in the person of the foolish as saying of the soul: the breath in our nostrils is smoke, and reason is a spark kindled by the beating of our hearts (Wis 2:2).

Against those who say that intellect and sense are the same

Some of the early philosophers came near to these, through thinking that intellect differs not from sense.¹ But this is impossible.

For sense is found in all animals, whereas animals other than man have no intellect. This is evident from the fact that they do diverse and opposite things not as though they had intelligence, but as moved by nature, performing certain determinate operations that are uniform within the same species: thus every swallow builds its nest in the same way. Therefore, intellect is not the same as sense.

Further. Sense is not cognizant except of singulars: for every sensitive power knows by individual species, since it receives the species of things in corporeal organs. But the intellect is cognizant of universals, as evidenced by experience. Therefore, intellect differs from sense.

Moreover. The knowledge of the senses does not extend beyond things corporeal. This is clear from the fact that sensible qualities, which are the proper objects of the senses, are only in corporeal things, and without them the senses know nothing. On the other hand, the intellect knows things incorporeal: for instance, wisdom, truth, and the relations of things. Therefore, intellect and sense are not the same.

Again. Sense knows neither itself nor its operation: for sight neither sees itself, nor sees that it sees, but this belongs to a higher power, as is proved in On the Soul.¹ But the intellect knows itself, and knows that it understands. Therefore, intellect is not the same as sense.

Against those who say that the possible intellect is the imagination

The opinion of those who held that the possible intellect is not distinct from the imagination¹ was akin to the foregoing. But this is evidently false.

For imagination is also in other animals. A sign of this is that in the absence of sensibles they shun or seek them, which would not be the case did they not retain an imaginary apprehension of them. But intellect is not in them, since they offer no evidence of intelligent action. Therefore, imagination and intellect are not the same.

Further. Imagination is only about things corporeal and singular, since the fancy is a movement caused by actual sensation, as stated in On the Soul.¹ But the intellect is about universals and incorporeal things. Therefore, the possible intellect is not the imagination.

Moreover. It is impossible for the same thing to be mover and moved. Now the phantasms move the possible intellect, as sensibles move the senses, as Aristotle states.¹ Therefore, the possible intellect cannot be the same as the imagination.

Hence it is said: who teaches us more than the beasts of the earth, and makes us wiser than the birds of the air (Job 35:11). By which we are given to understand that man has a cognitive power above sense and imagination, which are in other animals.

How an intellectual substance can be the form of the body

Accordingly, from the foregoing arguments we are able to conclude that an intellectual substance can be united to the body as its form.

For if an intellectual substance is not united to the body merely as its mover, as Plato stated, nor is in contact with it merely by the phantasms, as Averroes held, but as its form; and if the intellect by which man understands is not a preparedness in human nature (as Alexander maintained), nor the temperament (as Galen said), nor harmony (according to Empedocles), nor a body, the senses, or imagination (as the ancients asserted), it follows that the human soul is an intellectual substance united to the body as its form. This can be made evident as follows.

For one thing to be another’s substantial form, two conditions are required. One of them is that the form be the principle of substantial being to the thing of which it is the form. I speak not of the effective but of the formal principle, by which a thing is, and is called a being. Hence follows the second condition, namely, that the form and matter combine together in one being, which is not the case with the effective principle together with that to which it gives being. This is the being in which a composite substance subsists, which is one in being, and consists of matter and form. Now an intellectual substance, as proved above,¹ is not hindered by the fact that it is subsistent from being the formal principle of being to matter, as communicating its being to matter. For it is not unreasonable that the composite and its form itself should subsist in the same being, since the composite exists only by the form, nor does either subsist apart from the other.

It may, however, be argued that an intellectual substance cannot communicate its being to corporeal matter, so that the intellectual substance and the corporeal matter have together one being, because different genera have different modes of being, and a more noble mode belongs to a more noble substance.

This would be said reasonably if this being belonged in the same way to matter as to the intellectual substance. But it is not so. For it belongs to corporeal matter as its recipient and subject raised to something higher, while it belongs to the intellectual substance as its principle, and in accordance with its very nature. Therefore, nothing prevents an intellectual substance from being the human body’s form, which is the human soul.

In this way we are able to perceive the wondrous connection of things. For we always find the lowest in the higher genus touching the highest of the lower genus: thus some of the lowest of the animal kind scarcely surpass the life of plants—such as oysters, which are immovable, have only the sense of touch, and are fixed to the earth like plants. Hence blessed Dionysius says in On the Divine Names 7, that divine wisdom has united the ends of higher things with the beginnings of the lower. Accordingly, we may consider something supreme in the genus of bodies (namely, the well-tempered human body), which touches the lowest of the higher genus (namely, the human soul), and this occupies the last degree in the genus of intellectual substances, as may be seen from its mode of understanding. Hence it is that the intellectual soul is said to be on the horizon and confines of things corporeal and incorporeal,¹ inasmuch as it is an incorporeal substance, and yet the form of a body. And a thing composed of an intellectual substance and corporeal matter is not less one than that which results from the form of fire and its matter; but perhaps more so, since the more a form overcomes matter, the more one is that which is made from it and matter.

Now, though form and matter have one being, it does not follow that matter always equals the being of the form. In fact, the more noble the form, the more it surpasses matter in its being. This is clear to one who looks into the operations of forms, from the consideration of which we know their natures, since a thing operates according as it is. Consequently, a form whose operation surpasses the condition of matter also itself surpasses matter in the excellence of its being.

For we find certain lowest forms, which are capable of no operation except such as comes within the compass of the qualities which are the dispositions of matter—for instance, heat, cold, moisture and dryness, rarity, density, gravity and levity, and similiar others (like the elemental forms). Consequently, these forms are altogether material, and wholly merged in matter.

Above these we find the forms of mixed bodies; these, although they do not extend to any operations that cannot be accomplished through the aforesaid qualities, nevertheless sometimes produce those effects by a higher power which they receive from the heavenly bodies, and which is consequent upon their species; thus the lodestone attracts iron.

Again, above these we find certain forms whose operations include some which surpass the power of the aforesaid qualities, although the same qualities assist organically in their operation, such are the souls of plants. These again are like not only to the powers of heavenly bodies (in surpassing the active and passive qualities), but also to the movers of heavenly bodies, inasmuch as they are the principles of movement in living things, which move themselves.

Above these forms we find other forms like the higher substances not only in moving, but also in knowing—and thus they are capable of operations to which the aforesaid qualities do not help even organically. And yet these operations are not accomplished save by means of a corporeal organ; such are the souls of dumb animals. For sensation and imagination are not accomplished by heating and cooling, although these are necessary for the due disposition of the organ.

And above all these forms we find a form like the higher substances even as regards the kind of knowledge, which is intelligence: and thus it is capable of an operation which is accomplished without any corporeal organ at all. This is the intellective soul, for intelligence is not effected by a corporeal organ. Consequently, it follows that this principle by which man understands—namely, the intellective soul, which surpasses the condition of corporeal matter—is not wholly encompassed by and merged in matter, as are other material forms. This is indicated by its operation, in which corporeal matter has no part. And yet, since the human soul’s act of intelligence needs powers (namely, imagination and sense) which operate through corporeal organs, this by itself shows that the soul is naturally united to the body in order to complete the human species.

Solution of the arguments by which it was proved above that an intellectual substance cannot be united to the body as its form

Taking the foregoing¹ into consideration, it is not difficult to solve the arguments given above² against the aforesaid union.

In the first argument, something false is taken for granted. For body and soul are not two actually existing substances, but one actually existing substance is made from them, for man’s body is not actually the same while the soul is present and when the soul is absent, and it is the soul that makes it to be actually.

The statement in the second objection that form and matter belong to the same genus, is true not as though they were both species of the same genus, but because they are the principles of the same species. Accordingly, the intellectual substance and the body, which if they existed apart would be species of different genera, through being united are of the same genus as principles of it.

Nor does it follow that the intellectual substance is a material form, although its being is in matter, as the third argument contended. For it is not in matter as merged in matter, or wholly encompassed by matter, but in another way, as stated.

Nor does the intellectual substance being united to the body as its form prevent the intellect being separate from the body, as the philosophers say. For we must consider in the soul both its essence and its power. According to its essence, it gives being to such and such a body, while according to its power it accomplishes its proper operations. If, therefore, an operation of the soul be accomplished by means of a corporeal organ, it follows that the power which is the principle of that operation is the act of that part of the body by which its operation is accomplished: thus sight is the act of the eye. If, however, its operation be not accomplished by means of a corporeal organ, its power will not be the act of a body. It is in this sense that the intellect is said to be separate, and this does not preclude the substance of the soul of which the intellect is a power (or the intellective soul) from being the act of the body, as the form which gives being to such a body.

And although the soul by its substance is the form of the body, it is not necessary that its every operation be performed by means of the body, and that consequently its every power be the act of a body, as the fifth argument supposed. For it has been already shown that the human soul is not such a form as is wholly merged in matter, but is of all other forms raised highest above matter. Consequently, it can produce an operation without the body, as being independent of the body in operating, since not even in being does it depend on the body.

In the same way, it is clear that the reasons whereby Averroes tries to confirm his opinion¹ do not prove that the intellectual substance is not united to the body as its form.

For the expressions used by Aristotle in reference to the possible intellect, when he says that it is impassible, unmixed, and separate, do not oblige us to admit that the intellective substance is not united to the body as the form from which the latter has being. For they are also true if we say that the intellective power, which Aristotle calls the power of understanding,¹ is not the act of an organ, as though it exercised its operation thereby. This is, in fact, shown by his proof, since he proves that it is unmixed and separate from its operation whereby it understands all things, and because operation belongs to a power as to its principle.

Consequently, it is clear that neither does Aristotle’s proof show that the intellective substance is not united to the body as its form. For if we suppose that the soul’s substance is thus united to the body in being, and that the intellect is not the act of any organ, it will not follow that the intellect has a particular nature—I refer to the natures of sensibles, since it is not admitted to be a harmony,¹ nor the reason of an organ—as Aristotle says of sense that it is like the reason of an organ.² For the intellect does not have not a common operation with the body.

That Aristotle, by saying that the intellect is unshackled or separate, does not mean to exclude its being a part or power of the soul which is the form of the whole body, is clear from what he says at the end of On the Soul 1, against those who said that different parts of the soul are in different parts of the body: If the whole soul contains the whole body, it is fitting that each of its parts should contain some part of the body. But this seems impossible. For it is difficult to conceive what part the intellect contains, and how.¹

It is also evident, since the intellect is not the act of any part of the body, that its receptiveness is not that of prime matter, insofar as its receptiveness and operation are altogether without a corporeal organ.

Nor again is the infinite power of the intellect excluded, since its power is not ascribed to a magnitude, but is founded on the intellectual substance, as stated.

That according to the words of Aristotle we must say that the intellect is united to the body as its form

Now, since Averroes endeavors to confirm his opinion especially by appealing to the words and proof of Aristotle,¹ it remains to be shown that, according to Aristotle’s opinion, we must say that the intellect as to its substance is united to a body as its form.

For Aristotle in the Physics¹ proves that it is impossible to go on to infinity in movers and things moved. Hence he concludes that we must come to some first moved thing, which either is moved by an immovable mover, or moves itself. Of these two he takes the latter (namely, that the first movable moves itself) for this reason: that what is by a thing itself always precedes that which is by another. Then he shows that a self-mover is of necessity divided into two parts, one of which is mover and the other moved. Consequently, the first self-mover must consist of two parts—the one moving, the other moved. Now every such thing is animate.² Therefore, the first movable (namely, the heaven) is animate according to the opinion of Aristotle. Hence in On the Heavens 2³ it is expressly stated that the heaven is animate, and for this reason we must ascribe to the heaven differences of position not only in relation to us, but also in relation to itself.

Let us then inquire with what kind of soul the heaven is animated, according to Aristotle’s opinion.

In 11 Metaphysics,¹ he proves that we may consider, in the heaven’s movement, something that moves and is wholly unmoved, and something that moves and is also moved. Now that which moves and is wholly unmoved moves as an object of desire: nor is there doubt that it is desirable by that which is moved. And he shows that it moves not as desirable by the desire of concupiscence, which is the desire of sense, but as desirable by intellectual desire: therefore, he says that the first unmoved mover is desirable and intellectual. Consequently, that which is moved by it (namely, the heaven) is desiring and understanding in a more noble way than we are, as he proves further on. Therefore, the heaven is composed of an intellectual soul and a body, according to Aristotle’s opinion. He refers to this when he says in On the Soul 2 that in certain things there is the faculty and act of understanding—for instance, in men, and in any other like or more noble things,² namely, the heaven.

Now it is clear that the heaven does not have a sensitive soul, according to the opinion of Aristotle, since it would have various organs, which is not in keeping with the heaven’s simplicity. In order to point this out, Aristotle goes on to say that those corruptible things which have intellect have all the other powers,¹ so as to imply that some incorruptible things (namely, the heavenly bodies) have intellect without the other powers of the soul.

Therefore, it cannot be said that the intellect comes into contact with the heavenly bodies through phantasms: but we must say that the intellect, by its substance, is united to the heavenly body as its form.

Consequently, since the human body is the most noble of all lower bodies, and by the equability of its temperament is most like the heaven, which is free of all contrariety, it follows that in the opinion of Aristotle, the intellectual substance is united to the human body not by any phantasms, but as its form.

As regards what we have said about the heaven being animate, we have not said it as though we asserted it to be in keeping with the teaching of faith, to which it does not matter whether we state it to be so or otherwise. Hence Augustine says: nor do I consider it as certain whether the sun, moon, and all the stars belong to the same company, i.e., of the angels, although some think them to be bodies endowed with light, without sense or intelligence (Enchiridion, 58).

That the soul is united to the body immediately

We are able to conclude from the foregoing that the soul is united to the body immediately, nor must we admit any medium as uniting the soul to the body; whether it be the phantasms, as Averroes maintained;¹ or its powers, as some say; or the corporeal spirit, as others have asserted.

For it has been proved.¹ that the soul is united to the body as its form. Now a form is united to matter without any medium whatever, since to be the act of such and such a body is competent to a form by its very nature and not by anything else. Consequently, neither is there anything that makes one thing out of matter and form, except the agent which reduces the potency to act, as Aristotle proves in Metaphysics 8:² for matter and form are related as potency and act.

It may be said, however, that there is a medium between the soul and the body not in the point of being, but as regards movement and in the order of generation. As regards movement, since in the movement by which the soul moves the body there is a certain order among moved and movers. For the soul produces all its operations through its powers, so that it moves the body by means of its power, and again the members by means of the vital spirit, and again one organ by means of another. In the order of generation, dispositions to a form precede the form in matter, although they are posterior to it in being. Consequently, the body’s dispositions, by which it is rendered the proper perfectible subject of such and such a form, may in that sense be described as a medium between the soul and body.

That the whole soul is in the whole body and in each part thereof

From the same premises, we can prove that the whole soul is in the whole body, and in each part of it.

For the proper act must be in its proper perfectible subject. Now the soul is the act of an organic body,¹ not of one organ only. Therefore, it is in the whole body, and not only in one part, according to its essence by which it is the form of the body.

And the soul is the form of the whole body in such a way as to be also the form of each part. For were it the form of the whole and not of the parts, it would not be the substantial form of that body: thus the form of a house, which is the form of the whole and not of each part, is merely an accidental form. That it is the substantial form both of the whole and of the parts is clear from the fact that both the whole and the parts take their species from it. Hence, when it departs, neither whole nor parts retain the same species: for the eye or flesh of a dead person are only so called equivocally.¹ Accordingly, if the soul is the act of each part, and an act is in the thing of which it is the act, it follows that it is by its essence in each part of the body.

That this applies to the whole soul is evident. For, since whole denotes relation to parts, it follows that whole is taken in various senses, according to the various meanings of parts. Now part is taken in two ways. First, insofar as a thing is divided according to quantity; thus two cubits is a part of three cubits. Second, insofar as a thing is divided by a division of its essence; thus form and matter are said to be parts of a composite. Hence a whole is spoken of in reference both to quantity and to essential perfection. Now whole and part in reference to quantity are not applicable to forms save accidentally, namely, insofar as they are divided when the quantitative subject is divided. On the other hand, whole or part in reference to essential perfection is found in forms by their very nature. Speaking, then, of this kind of totality, which is applicable to forms by their very nature, it is clear regarding every form that the whole of it is in the whole [subject], and the whole of it in each part of it: for just as whiteness is in a whole body in respect of the whole essence of whiteness, so is it in each part of it. It is otherwise with the totality which is ascribed to forms accidentally, for in this sense we cannot say that the whole whiteness is in each part. Accordingly, if there be a form that is not divided when its subject is divided, like the souls of perfect animals, there will be no need for a distinction, since only one totality is applicable to them: and we must say absolutely that the whole of it is in each part of the body. Nor is this difficult to conceive for one who understands that the soul is not indivisible in the same way as a point, and that an incorporeal is not united to a corporeal being in the same way as bodies are united together, as we have expounded above.¹

Nor is it inconsistent that the soul, since it is a simple form, should be the act of parts so various. For the matter of every form is adapted to it according to its requirements. Now the more noble and simple a form is, the greater is its power. Consequently, the soul, which is the noblest of the lower forms, is manifold in power and has many operations, though simple in substance. Therefore, it needs various organs in order to accomplish its operations, of which organs the various powers of the soul are said to be the acts—for instance, sight of the eye, hearing of the ears, and so forth. For this reason, perfect animals have the greatest variety of organs, while plants have the least.

This explains why certain philosophers have stated that the soul is in some particular part of the body: thus Aristotle¹ says that it is in the heart, because one of its powers is ascribed to that part of the body. For the motive power, of which Aristotle was treating in that book, is chiefly in the heart, by which the soul communicates movement and other like operations to the whole body.

That there is not one possible intellect in all men

From what has been said it is evidently shown that there is not one possible intellect of all present, future, and past men, as Averroes fancies.¹

For it has been proved that the substance of the intellect is united to the human body as its form.¹ Now one form cannot possibly be in more than one matter, because the proper act is produced in its proper potency, since they are mutually proportionate. Therefore, there is not one intellect of all men.

Again. Proper instruments are due to every mover, for the piper uses one kind of instrument, and the builder another. Now the intellect is compared to the body as the latter’s mover, as Aristotle declares in On the Soul 3.¹ Therefore, just as it is impossible for the builder to use the instruments of a piper, so is it impossible for the intellect of one man to be the intellect of another.

Moreover. A thing has being and unity from the same cause: for one and being are consequent upon one another. Now every thing has being through its form. Therefore, the unity of a thing is consequent upon the unity of the form. Consequently, it is impossible that there should be one form of several individuals. Now the form of this individual man is his intellective soul. Therefore, there cannot possibly be one intellect of all men.

If, however, it be said that the sensitive soul of this man is distinct from the sensitive soul of that one, and to that extent there is not one man, although there is one intellect; this cannot stand. For each thing’s proper operation is a consequence and an indication of its species. Now just as the proper operation of an animal is sensation, so the operation proper to man is understanding, as Aristotle says in Ethics 1.¹ Hence it follows that just as this individual is an animal by reason of sense, according to Aristotle in On the Soul 2,² so is he a man by reason of that whereby he understands. But that whereby the soul—or man through the soul—understands is the possible intellect, as stated in On the Soul 3.³ Therefore, this individual is a man through the possible intellect. Consequently, if this man has a distinct sensitive soul from that man’s, and yet not a distinct possible intellect, but one and the same, it will follow that they are two animals, but not two men. This is clearly impossible. Therefore, there is not one possible intellect of all men.

The said Commentator replies to these arguments, in On the Soul 3 (above, ch. 59), by saying that the possible intellect comes into contact with us by its form—that is, by the intelligible species—the subject of which is the phantasma existing in us, and which is distinct in distinct subjects. Therefore, the possible intellect is individualized in different subjects not by reason of its substance, but by reason of its form.

It is clear from what has been said above that this reply is of no avail. For it was shown above¹ that it is impossible for man to understand if the possible intellect merely comes thus into contact with us.

And granted that the said contact were sufficient for man to have intelligence, nevertheless the reply adduced does not solve the arguments given above. For according to the opinion in question, nothing pertaining to the intellect will be individualized according to the number of men, excepting only the phantasm. And this very phantasm will not be individualized according as it is actually understood, because it is thus in the possible intellect, and abstracted from material conditions by the active intellect. Now the phantasm, as understood potentially, does not surpass the degree of the sensitive soul. Consequently, this man will still remain indistinct from that one, except as regards the sensitive soul: and there will follow the absurdity already indicated, that this and that man are not several men.

Again. That through which a living thing derives its species is its first and not its second perfection, as Aristotle states in On the Soul 2 (above, ch. 61). But the phantasm is not the first but a second perfection, because the imagination is movement caused by sense in act, as stated in On the Soul.¹ Therefore, it is not from the individual phantasm that man derives his species.

Moreover. Phantasms that are understood potentially are of various kinds. Now that from which a thing derives its species ought to be one, since of one thing there is one species. Therefore, man does not derive his species through the phantasms as individualized in various subjects, in which way they are understood potentially.

Again. That from which a man derives his species must always remain the same in the same individual as long as the individual lasts, or else the individual would not always be of one and the same species, but sometimes of this one, and sometimes of that one. Now the phantasms do not always remain the same in one man, but some come anew while other previous ones pass away. Therefore, the human individual neither derives his species through the phantasm, nor comes by it into touch with the principle of his species, which is the possible intellect.

If, however, it be said that this man derives his species not from the phantasms themselves, but from the powers in which the phantasms reside—namely, those of imagination, memory, and cogitation (which latter is proper to man and is called by Aristotle in On the Soul 3 (above, ch. 30) the passive intellect)—still the same impossibilities follow. For, since the cogitative power has an operation only about particulars (the intentions of which it composes and divides), and has a corporeal organ by which it acts, it does not surpass the genus of the sensitive soul. Now man, by his sensitive soul, is not a man but an animal. Therefore, it still remains that the only thing which is numbered in us is that which belongs to man as an animal.

Further. The cogitative power is not directed to the possible intellect by which man understands except through its act by which the phantasms are prepared, so that by the active intellect they may be made actually intelligible, and perfect the possible intellect. Now this operation does not always remain the same in us. Consequently, it is impossible for man either to be brought by it into contact with the principle of the human species, or to receive its species from it. Therefore, it is evident that the above reply is to be utterly rejected.

Again. That by which a thing operates or acts is a principle to which the operation is a sequel not only as to its being, but also in the point of multitude or unity, since from the same heat there is only one heating or active calefaction, although to be heated or passive calefaction may be manifold, according to the diversity of things heated simultaneously by the same heat. Now the possible intellect is whereby the soul understands, as Aristotle states in On the Soul 3.¹ Consequently, if the possible intellect of this and that man is one and the same in number, the act of intelligence will of necessity be one and the same in both. But this is clearly impossible, since the one operation cannot belong to different individuals. It is, therefore, impossible for this and that man to have the one possible intellect.

And if it be said that the very act of understanding is multiplied according to the difference of phantasms, this cannot stand. For, as we have stated, the one action of the one agent is multiplied only according to the different subjects into which that action passes. But understanding, willing, and the like are not actions that pass into outward matter, but remain in the agent himself, as perfections of that same agent, as Aristotle declares in Metaphysics 9.¹ Therefore, one act of understanding of the possible intellect cannot be multiplied by reason of a diversity of phantasms.

Again. The possible intellect understands man, not as this man, but as man simply, as regards his specific nature. Now this nature is one, however much the phantasms of man be multiplied, whether in one man or in several, according to the various human individuals, which properly speaking the phantasms represent. Consequently, the multiplication of phantasms cannot cause the multiplication of the possible intellect’s act of understanding in respect of one species. Hence it will still follow that there is one identical act of several men.

Again. The possible intellect is the proper subject of the habit of science, because its act is to consider according to science. Now an accident, if it be one, is not multiplied except according to the subject. Consequently, if there be one possible intellect of all men, it will follow of necessity that the same specific habit of science (for instance, the habit of grammar) is identically the same in all men, which is unthinkable. Therefore, the possible intellect is not one in all.

To this, however, they reply that the subject of the habit of science is not the possible intellect, but the passive intellect and the cogitative power.¹

But this cannot be. For, as Aristotle proves, in Ethics 2, from like acts like habits are formed which again produce like acts.¹ Now the habit of science is formed in us by acts of the possible intellect, and we are capable of performing the same acts according to the habit of science. Therefore, the habit of science is in the possible, not the passive, intellect.

Further. Science is about the conclusions of demonstrations: for a demonstration is a syllogism that makes us know scientifically, as Aristotle states in Posterior Analytics 1.¹ Now the conclusions of demonstrations are universal like their premises. Therefore, science will be in the power that is cognizant of universals. Now the passive intellect is not cognizant of universals, but of particular intentions. Therefore, it is not the subject of the scientific habit.

Seemingly, the fallacy of placing the habit of science in the passive intellect arose from the fact that men are observed to be more or less apt for the considerations of sciences according to the various dispositions of the cogitative and imaginative powers.

But this aptitude depends on these powers as on remote dispositions, in the same way as it depends on perfection of touch and bodily temperament, in which sense Aristotle says in On the Soul 2 that men of perfect touch and of soft flesh are well apt of mind.¹ But from the habit of science there results an aptitude for consideration as from the proximate principle of that action, because the habit of science must perfect the power whereby we understand, so that it act easily at will even as other habits perfect the powers in which they reside.²

Again. The dispositions of the aforesaid powers are on the part of the object, namely of the phantasm, which, on account of the goodness of these powers, is prepared in such a way as easily to be made actually intelligible by the active intellect. Now the dispositions on the part of the objects are not habits, but those dispositions are which are on the part of the powers: for the habit of fortitude is not the disposition by which fearsome objects become objects of endurance, but a habit whereby a part of the soul—namely, the irascible—is disposed to endure fearsome objects. It is consequently evident that the habit of science is not in the passive intellect, as the said Commentator asserts, but rather in the possible intellect.

Again. If there is one possible intellect for all men, it must be allowed that if, as they assert, men have been always, the possible intellect has always existed, and much more the active intellect, since the agent is more noble than the patient, as Aristotle says.¹ Now if the agent is eternal, and the recipient eternal, the things received must be eternal. Consequently, the intelligible species were from eternity in the possible intellect. Hence it does not receive any intelligible species anew. But sense and imagination are not required for anything to be understood except that the intelligible species may be derived from them. Therefore, neither sense nor imagination will be necessary for understanding. And we shall come back to Plato’s opinion that we do not acquire knowledge from the senses, but that we are awakened by them to the recollection of things we knew before.²

To this the said Commentator replies¹ that the intelligible species have a twofold subject, from one of which (namely the possible intellect) they derive eternity, while from the other (namely, the phantasm) they derive newness: even as the subject of the visible species is twofold (namely, the object outside the soul, and the faculty of sight).

But this reply cannot stand. For it is impossible that the action and perfection of an eternal thing should depend on something temporal. Now phantasms are temporal, being renewed daily by virtue of the senses. Consequently, the intelligible species by which the possible intellect is made actual and operates cannot depend on the phantasms, as the visible species depends on things that are outside the soul.

Moreover. Nothing receives what it already has, because the recipient must be void of the thing received, according to Aristotle.¹ Now the intelligible species, before my or your sensation, were in the possible intellect, for those who were before us would not have understood unless the possible intellect had been reduced to act by the intelligible species. Nor can it be said that these species already received into the possible intellect have ceased to exist, because the possible intellect not only receives but also keeps what it receives; hence in the On the Soul 3 it is called the abode of species.² Consequently, species are not received from our phantasms into the possible intellect. Therefore, it were useless for our phantasms to be made actually intelligible by the active intellect.

Again. The thing received is in the recipient according to the mode of the recipient.¹ But the intellect is in itself above movement. Therefore, what is received into it is received fixedly and immovably.

Moreover. It is useless to say that in natural things what is acquired by movement does not remain but immediately ceases to be, since the opinion of those who say that all things are ever in motion is repudiated, because movement must terminate in repose. Much less, therefore, can it be said that what is received into the possible intellect is not retained.

Again. If the possible intellect does not receive any intelligible species from the phantasms that are in us because it has already received from the phantasms of those who were before us, for the same reason it receives from none of the phantasms of those who were preceded by others. But if the world is eternal, as they say, every person was preceded by some others. Consequently, the possible intellect never receives any species from the phantasms. Therefore, it was useless for Aristotle to posit the active intellect in order to make the phantasms actually intelligible.¹

And if it be said that for the same reason we should not need a phantasm in order to consider the things the species of which are retained in the possible intellect, even if different persons have different possible intellects—which is contrary to Aristotle, who says that the soul by no means understands without a phantasm¹—it is evident that this objection is to no purpose. For the possible intellect, like every substance, operates according to the mode of its nature. Now, according to the mode of its nature it is the form of the body. Therefore, it indeed understands immaterial things, but it considers them in something material. A sign of this is that in teaching universal principles we propose particular examples, so that our statements are viewed in them. Consequently, the possible intellect is related in one way to its necessary phantasm before having the intelligible species, and in another way after receiving the intelligible species. For before, it needs it in order to receive from it the intelligible species; hence it stands in relation to the possible intellect as the object moving it. But after the species has been received into it, it needs the phantasm as the instrument or foundation of its species: hence it is related to the phantasm as efficient cause. For by the command of the intellect there is formed in the imagination a phantasm corresponding to such and such an intelligible species, and in this phantasm the intelligible species is reflected as an exemplar in the exemplate or image. Accordingly, if the possible intellect had always had the species, it would never be compared to the phantasms as the recipient to the object moving it.

Again. The possible intellect is that by which the soul and man understand, according to Aristotle.¹ If, however, the possible intellect be one in all and eternal, it follows that it already received all the intelligible species of the things that are or have been known by any men whatsoever. Therefore, each one of us who understands by the possible intellect—in fact, whose act of understanding is the possible intellect’s own act of understanding—will understand all that is or has been understood by anyone: which is clearly false.

To this the aforesaid Commentator replies by saying that we do not understand by the possible intellect, except insofar as it is in contact with us through our phantasms. And since phantasms are not the same in all, nor arranged in the same way, neither is whatever one person understands understood by another. Also this reply would seem to accord with what has been stated above, becaue even if the possible intellect is not one, we do not understand the things whose species are in the possible intellect without the presence of phantasms disposed for that purpose.

That this reply cannot wholly avoid the difficulty is proved thus. When the possible intellect has been made actual by the reception of the intelligible species, it can act of itself, as Aristotle says in On the Soul 3.¹ Hence we observe that when we have once received knowledge of a thing, it is in our power to consider it again at will. Nor are we hindered on account of phantasms, because it is in our power to form phantasms adapted to the consideration that we wish to make—unless, perhaps, there be an obstacle on the part of the organ to which the phantasm appertains, as happens in madmen and those suffering from lethargy, who cannot freely exercise their imagination and memory. For this reason Aristotle says in Physics 8² that one who already has the habit of science, although he be considering potentially, needs no mover to reduce him from potency to act except one that removes an obstacle, but is able at will to proceed to actual consideration. Now, if the intelligible species of all sciences be in the possible intellect, which we must admit if it be one and eternal, the intellect will need phantasms in the same way as one who already has science needs them in order to consider according to that science, which also it cannot do without phantasms. Since, then, every man understands by the possible intellect insofar as it is reduced to act by the intelligible species, every man will be able to consider at will the things known in every science. This is clearly false, for thus no one would need a teacher in order to acquire a science. Therefore, the possible intellect is not one and eternal.

The position of Avicenna, however, seems to clash with the arguments given above. For he says in his book On the Soul¹ that the intelligible species do not remain in the possible intellect except when they are being actually understood.

He endeavors to prove this because as long as the apprehended forms remain in the apprehensive power, they are actually apprehended, since sense is made actual through being identified with the thing actually sensed, and likewise the intellect, when actual is identified with the thing actually understood.¹ Hence it seems that whenever sense or intellect becomes one with the thing sensed or understood, through having its form, there is actual apprehension through sense or intellect. And he says that the powers which preserve the forms not actually apprehended are not apprehensive powers, but storehouses of the apprehensive faculties. For instance, according to him, the imagination, which is the storehouse of forms apprehended by the senses, and the memory, is the storehouse of intentions apprehended without the senses (as when the sheep apprehends the enmity of the wolf). And it so happens that these powers preserve forms which are not actually apprehended insofar as they have certain corporeal organs in which forms are received in a manner akin to apprehension. For which reason the apprehensive power, by turning to these store-houses, apprehends actually. Hence he concludes that it is impossible for the intelligible species to be preserved in the possible intellect, except while it understands actually. It follows then either that the intelligible species themselves are preserved in some corporeal organ or some power having a corporeal organ; or else that intelligible forms exist of themselves, and that our possible intellect is compared to them as a mirror to the things which are seen in a mirror; or again that whenever the possible intellect understands actually, the intelligible species are infused anew into the possible intellect by a separate agent. Now the first of these three is impossible, because forms existing in powers which use corporeal organs are only potentially intelligible, while the second is the opinion of Plato, which Aristotle refutes in his Metaphysics.² Therefore, he concludes by accepting the third, namely that whenever we understand actually, the intelligible species are infused into our possible intellect by the active intellect, which he asserts to be a separate substance.

And if anyone argues against him that then there is no difference between a man when he first learns, and when afterwards he wishes to consider actually what he has previously learnt, he replies that to learn is merely to acquire the perfect aptitude for uniting oneself with the active intelligence so as to receive the intelligible form from it. Therefore, before learning there is in man a mere potency for such a reception, and to learn is, as it were, the potency adapted.

Moreover, it would seem to be in agreement with this position that Aristotle, in his book On Memory 1, proves that the memory is not in the intellective faculty, but in the sensitive part of the soul. Hence it seems to follow that the preserving of the species does not belong to the intellective part.

Nevertheless, if we consider it carefully, this position, as regards its origin, differs little or not at all from that of Plato. For Plato asserted that intelligible forms are separate substances, from which knowledge flows into our souls, while he (Avicenna) affirms that knowledge flows into our souls from one separate substance which, according to him, is the active intellect. Now, as regards the manner of acquiring knowledge, it does not matter whether our knowledge be caused by one or several separate substances, since in either case it follows that our knowledge is not caused by sensible objects. The contrary of this is proved by the fact that a person who lacks one sense also lacks the knowledge of the sensibles known through that sense.

Moreover, it is a pure invention to say that the possible intellect is enlightened with the light of the active intellect so as to know the universal through considering singulars which are in the imagination, as is the statement that the actions of the lower powers (namely, of the imagination, memory, and cogitative powers) adapt the soul to receive the emanation of the active intellect. For we see that our soul is the more disposed to receive from separate substances according as it is further removed from corporeal and sensible things, since by withdrawing from that which is below, one approaches to that which is above. Therefore, it is not likely that the soul is disposed to receive the influence of a separate intelligence by considering corporeal phantasms.

Plato, however, was more consistent with the principle on which his position was based. For he held that sensibles do not dispose the soul to receive the influence of separate forms, but merely arouse the intellect to consider the things the knowledge of which it had received from an external cause. For he maintained that knowledge of all things knowable was caused in our souls from the outset by separate forms; hence he said that to learn is a kind of remembering. In fact, this is a necessary consequence of his position, because since separate substances are immovable and unchangeable, the knowledge of things is always reflected from them in our soul, which is capable of that knowledge.

Moreover. That which is received in a thing is in it according to the mode of the recipient. Now the being of the possible intellect is more stable than the being of corporeal matter. Therefore, since forms that flow into corporeal matter from the active intelligence are preserved in that matter (according to him), much more are they preserved in the possible intellect.

Again. Intellective knowledge is more perfect than sensitive. Therefore, if there is something to preserve things apprehended in sensitive knowledge, all the more will this be the case in intellective knowledge.

Again. We find that when various things belong to various powers in a lower order of powers, in a higher order they belong to one: thus the common sense apprehends the objects sensed by all the proper senses. Hence to apprehend and to preserve, which belong to different powers in the sensitive part of the soul, must be united in the highest power, the intellect.

It is also clear that this position is in conflict with the opinion of Aristotle in On the Soul 3,¹ who says that the possible intellect is the abode of the species, which is the same as to say that it is the storehouse of intelligible species, to use the words of Avicenna.

Again. He adds further on that when the possible intellect acquires knowledge, it is capable of acting by itself,¹ although it understand not actually. Therefore, it does not need the influence of any higher agent.

He also says in Physics 8¹ that before learning, man is in essential potency to knowledge, and consequently needs a mover by which to be reduced to act; but after he has already learnt, he needs no mover essentially. Therefore, he does not need the influence of the active intellect.

He also says in On the Soul 3 that the phantasms are to the possible intellect what sensibles are to the senses.¹ Therefore, it is clear that the intelligible species result in the possible intellect from the phantasms and not from a separate substance.

As to the arguments which would seem to favor the contrary, it is not difficult to solve them. For the possible intellect is in perfect act in respect of the intelligible species when it considers actually, but when it does not actually consider, it is not in perfect act, but is in a state between potency and act. This is what Aristotle says in On the Soul 3: when this part, the possible intellect, is identified with a thing, it is said to know it actually. And this happens when it is capable of acting by itself. Even thus it is also somewhat in potency, but not in the same way as before learning or discovering.¹

The memory is assigned to the sensitive part because it is of something as conditioned by a determinate time, for it is only of what is past. Consequently, since it does not abstract from singular conditions, it does not belong to the intellective part, which is of universals. Yet this does not preclude the possible intellect being able to preserve intelligibles which abstract from all particular conditions.

Solution of the arguments which would seem to prove the unity of the possible intellect

We must now show the inefficacy of such arguments as are adduced to prove the unity of the possible intellect.¹

For seemingly every form that is one specifically and many in number is individualized by matter, since things that are one in species and many in number agree in form and differ in matter. Therefore, if the possible intellect is multiplied numerically in different men, when it is one in species, it must be individualized in this and that man by matter. This is not, however, by matter which is a part of the intellect itself, because then its reception would be of the same kind as that of prime matter, and it would receive individual forms, which is contrary to the nature of the intellect. It follows, therefore, that it is individualized by matter which is the human body of which it is supposed to be the form. Now every form that is individualized by matter of which it is the act is a material form. For the being of a thing must depend on that from which it has its individuality: for just as common principles belong to the essence of the species, so individualizing principles belong to the essence of this particular individual. Hence it follows that the possible intellect is a material form, and consequently that it neither receives anything nor operates without a corporeal organ. And this again is contrary to the nature of the possible intellect. Therefore, the possible intellect is not multiplied in different men, but is one for all.

Again. If there were a different possible intellect in this and that man, it would follow that the species understood is numerically distinct in this and that man, though one specifically: for, since the possible intellect is the proper subject of species actually understood, if there be many possible intellects, the intelligible species must be multiplied numerically in different intellects. Now species or forms that are the same specifically and different numerically are individual forms. But these cannot be intelligible, since intelligibles are universal, not particular. Therefore, it is impossible for the possible intellect to be multiplied in different human individuals, and consequently it must be one in all.

Again. The master imparts the knowledge that he possesses to his disciple. Either, then, he imparts the same knowledge numerically, or he imparts a knowledge that is different numerically but not specifically. The latter is apparently impossible, since then the master would cause his knowledge to be in his disciple, as he causes his form to be in another by begetting one like to him in species; and this would seem to apply to material agents. It follows, therefore, that he causes the same knowledge numerically to be in his disciple. But this would be impossible unless there were one possible intellect for both. Therefore, seemingly there must be but one possible intellect for all men.

Nevertheless, just as the aforesaid position is void of truth, as we have proved,¹ so the arguments adduced in support of it are easy to solve.

For we contend that while the possible intellect is specifically one in different men, it is nevertheless many numerically, yet so as not to lay stress on the fact that the parts of a man do not by themselves belong to the genus or species, but only as principles of the whole. Nor does it follow that it is a material form dependent on the body as to its being. For just as it is competent to the human soul in respect of its species to be united to a body of a particular species, so this particular soul differs only numerically from that one through having a habitude to a numerically different body. Thus human souls are individualized—and consequently the possible intellect also which is a power of the soul—in relation to the bodies, and not as though their individuality were caused by their bodies.

His second argument fails through not distinguishing between that by which one understands and that which is understood. For the species received into the intellect is not that which is understood. For, since all arts and sciences are about things understood, it would follow that all sciences are about species existing in the possible intellect. And this is clearly false, for no science takes any consideration of such things except logic and metaphysics. Nevertheless, whatever there is in all the sciences is known through them. Consequently, in the process of understanding, the species received into the possible intellect is as the thing by which one understands, and not as that which is understood: even as the colored image in the eye is not that which is seen, but that by which we see. On the other hand, that which is understood is the very essence of the things existing outside the soul, even as things outside the soul are seen by corporeal sight, since arts and sciences were devised for the purpose of knowing things as existing in their respective natures.

Nor does it follow that, because science is about universals, universals are subsistent of themselves outside the soul, as Plato maintained. For, although true knowledge requires that knowledge correspond to things, it is not necessary that knowledge and thing should have the same mode of being. Because things that are united in reality are sometimes known separately: thus a thing is at once white and sweet, yet sight knows only the whiteness, and taste only the sweetness. So too the intellect understands a line existing in sensible matter apart from the sensible matter, although it can also understand it with sensible matter. Now this difference occurs according to the difference of intelligible species received into the intellect: for the species is sometimes an image of quantity alone, and sometimes is an image of a quantitative sensible substance. In like manner, although the generic and specific natures are never save in particular individuals, yet the intellect understands the specific and generic natures without understanding the individualizing principles: and this is to understand universals. And thus these two are not incompatible, namely, that universals do not subsist outside the soul, and that the intellect understands things that are outside the soul in understanding universals. That the intellect understands the generic or specific nature apart from the individualizing principles results from the condition of the intelligible species received into it, for it is rendered immaterial by the active intellect, through being abstracted from matter and material conditions whereby a particular thing is individualized. Consequently, the sensitive powers are unable to know universals, because they cannot receive an immaterial form since they always receive in a corporeal organ.

Therefore, it does not follow that the intelligible species is numerically one in this and that person who understand: for the result of this would be that the act of understanding in this and that person is numerically one, since operation follows the form which is the principle of the species. But in order that there be one thing understood, it is necessary that there be an image of one and the same thing. And this is possible if the intelligible species be numerically distinct: for nothing prevents several distinct images being made of one thing, and this is how one man is seen by several. Hence it is not incompatible with the intellect’s knowledge of the universal that there be several intelligible species in several persons.

Nor does it follow from this, if intelligible species be several in number and specifically the same, that they are not actually intelligible but only potentially, like other individual things. For individuality is not incompatible with actual intelligibility, since it must be admitted that, if we suppose them to be separate substances, both possible and active intellects are individual things not united to the body and subsistent of themselves, and yet they are intelligible. But it is materiality that is incompatible with intelligibility: a sign of this is that for forms of material things to be actually intelligible, they need to be abstracted from matter. Consequently, in those things in which individualization is effected by particular signate matter, the things individualized are not actually intelligible. But if individualization is not the result of matter, nothing prevents things that are individual from being actually intelligible. Now intelligible species, like all other forms, are individualized by their subject which is the possible intellect. Therefore, since the possible intellect is not material, it does not deprive the species which it individualizes of actual intelligibility.

Again. The possible intellect, according to the same Commentator, is the last in the order of intelligible substances, which in his opinion are several. Nor can it be denied that some of the higher substances are cognizant of the things which the possible intellect knows, since, as he says himself, the forms of the effects caused by the movement of a sphere are in the movers of the spheres. Hence it will still follow that, even if there be one possible intellect, the intelligible forms are multiplied in different intellects.

And although we have stated that the intelligible species received into the possible intellect is not that which is understood, but that whereby one understands, this does not prevent the intellect from understanding itself, its act of intelligence, and the species by which it understands by a kind of reflexion. In fact, it understands its act of intelligence in two ways: first in particular, for it understands that it understands in a particular instance; second, in general, inasmuch as it argues about the nature of its act. Consequently, it understands both the intellect and the intelligible species in two ways: both by perceiving its own existence and that it has an intelligible species, which is a kind of particular knowledge, and by considering its own nature and that of the intelligible species, which is a kind of universal knowledge. In this latter sense, we treat of the intellect and things intelligible in sciences.

From what has been said, the solution to the third argument is also evident. For his statement—that knowledge in the disciple and in the master is numerically one—is partly true and partly false. It is numerically one as regards the thing known, but not as regards the intelligible species by which it is known, nor again as regards the habit itself of knowledge. And yet it does not follow that the master causes knowledge in the disciple in the same way as fire generates fire, since things are not generated in the same way by nature as by art. For fire generates fire naturally, by reducing matter from potency to the act of its form, whereas the master causes knowledge in his disciple after the manner of art, since to this purpose is assigned the art of demonstration which Aristotle teaches in the Posterior Analytics; for a demonstration is a syllogism that makes us know.¹

It must, however, be observed, in accordance with Aristotle’s teaching in Metaphysics 7,¹ that there are some arts in which the matter is not an active principle productive of the art’s effect. Such is the art of building, since in timber and stone there is not an active force tending to the production of a house, but merely a passive aptitude. On the other hand, there is an art whose matter is an active principle tending to produce the effect of the art. Such is the medical art, since in the sick body there is an active principle conducive to health. Consequently, the effect of an art of the first kind is never produced by nature but is always the result of the art. But the effect of an art of the second kind is the result both of art and of nature without art: for many are healed by the action of nature without the art of medicine. In those things that can be done both by art and by nature, art imitates nature;² for if a person is taken ill through a cold cause, nature cures him by heating. Now the art of teaching is like this art. For in him that is taught, there is an active principle conducive to knowledge (namely, the intellect), and those things which are naturally understood (namely, first principles). Therefore knowledge is acquired in two ways, both by discovery without teaching, and by teaching. Consequently, the teacher begins to teach in the same way as the discoverer begins to discover, namely, by offering to the disciple’s consideration principles known by him (since all learning results from preexisting knowledge),³ and by drawing conclusions from those principles; and again by proposing sensible examples, from which there result, in the disciple’s mind, the phantasms which are necessary for his understanding. And since the outward action of the teacher would have no effect without the inward principle of knowledge, which is in us from God, among theologians it is said that man teaches by outward ministration, but God by inward operation. Even so the physician is said to minister to nature when he heals. Accordingly, knowledge is caused in the disciple by his master not by way of natural action, but after the manner of art, as stated.

That the active intellect is not a separate substance but part of the soul

From the foregoing we may also conclude that neither is there one active intellect in all, as Alexander and Avicenna maintained, who do not hold that there is one possible intellect in all.

For, since agent and recipient are mutually proportionate, it follows that to every patient there corresponds a proper agent. Now the possible intellect is compared to the active as the proper patient or recipient of the latter, since it is related to it as art to matter, as stated in On the Soul 3.¹ Hence if the possible intellect is part of the human soul, and multiplied according to the number of individuals, as we have shown,² the active intellect also will be the like, and not one for all.

Again. The active intellect makes the species to be actually intelligible not so that it itself may understand by them (especially as a separate substance), since it is not in potency, but so that the possible intellect may understand by them. Therefore, it does not make them otherwise than as required by the possible intellect so that it may understand. But it makes them to be such as it is itself, since every agent produces its like.¹ Therefore, the active intellect is proportionate to the possible intellect: consequently, since the possible intellect is a part of the soul, the active intellect is not a separate substance.

Moreover. Just as prime matter is perfected by natural forms which are outside the soul, so the possible intellect is perfected by forms actually understood. Now natural forms are received into prime matter not by the action of only one separate substance, but by the action of a form of the same kind—namely, of a form that is in matter—even as this particular flesh is begotten through a form that is in this particular flesh and bones, as Aristotle proves in Metaphysics 7.¹ Consequently, if the possible intellect is a part of the soul and not a separate substance, as we have shown,² the active intellect, by whose action the intelligible species result in it, will not be a separate substance, but an active force of the soul.

Again. Plato held that knowledge in us is caused by ideas, which he affirmed to be separate substances; and Aristotle refutes this opinion in Metaphysics 1.¹ Now it is clear that our knowledge depends on the active intellect as its first principle. If, then, the active intellect were a separate substance, there would be little or no difference between this opinion and Plato’s, which was refuted by the Philosopher.

Again. If the active intellect be a separate substance, its action must be continuous and uninterrupted, or at least we must say that it is not continued or interrupted at our will. Now its action is to make phantasms actually intelligible. Either, therefore, it will do this always, or not always. If not always, this will nevertheless not be at our discretion. Now, we understand actually when the phantasms are made actually intelligible. Consequently, it follows that either we always understand, or that it is not in our power to understand actually.

It may be said, however, that the active intellect for its own part is always active, but that the phantasms are not always made actually intelligible, but only when they are disposed to it. Now, they are disposed to it by the act of the cogitative power, the use of which is in our power. Consequently, to understand actually is in our power. It is for this reason that not all men understand the things of which they have the phantasms, since not all have the requisite act of the cogitative power, but only those who are instructed and accustomed.

Nevertheless, this reply seems not quite sufficient. For this disposition to understand, which is effected by the cogitative power, must either be a disposition of the possible intellect to receive intelligible forms emanating from the active intellect, as Avicenna maintains, or a disposition of the phantasms to be made actually intelligible, as Averroes and Alexander assert. Now, the former would seem improbable. Because the possible intellect by its very nature is in potency with regard to species actually intelligible; hence it stands in the same relation to them as a transparent body to light or to colored images. And if a thing by its very nature is capable of receiving a certain form, it needs no further disposition to that form, unless perhaps it contain contrary dispositions, as the matter of water is disposed to the form of air by the removal of cold and density. But there is nothing contrary in the possible intellect to prevent it receiving any intelligible species whatsoever, since the intelligible species even of contraries are not themselves contrary in the intellect, as Aristotle proves in Metaphysics 7,¹ for one is the reason for knowing the other. And the falsity which is incidental to the intellect’s judgment in composition and division does not result from the presence in the intellect of certain things understood, but from its lack of certain things. Therefore, the possible intellect, for its own part, requires no preparation in order to receive the intelligible species emanating from the active intellect.

Again. According to this the phantasms, and consequently the senses, would not be of themselves necessary for us to understand, but only accidentally, as it were inciting and preparing the possible intellect to receive. This is part of the Platonist theory, and contrary to the order which Aristotle assigns to the generation of art and science, in the first book of Metaphysics¹ and the last book of Posterior Analytics, where he says that memory results from sensation; experience from many memories; from many memories the universal apprehension, which is the beginning of science and art.²

This opinion of Avicenna, however, is in keeping with what he says about the generation of natural things.¹ For he holds that all lower agents, by their actions, prepare matter to receive the forms which emanate from a separate active intelligence into their respective matters. Hence for the same reason he also holds that the phantasms prepare the possible intellect; and that the intelligible forms emanate from a separate substance.

In like manner, if it be supposed that the active intellect is a separate substance, it seems unreasonable that the phantasms should be prepared by the cogitative power in order that they be actually intelligible and move the possible intellect. For this is seemingly in keeping with the opinion of those who say that the lower agents merely dispose to the ultimate perfection, and that this ultimate perfection is caused by a separate agent. This is contrary to the opinion of Aristotle in Metaphysics 7.¹ For it would seem that the human soul is not less perfectly equipped for understanding than the lower things of nature for their proper operations.

Moreover. In this lower world, the more noble effects are produced not by higher agents alone, but also require agents of their own genus, for the sun and man generate a man.¹ In like manner, we observe that in other perfect animals, some of the lower animals are generated by the mere action of the sun, without an active principle of their own genus (for instance, animals engendered of putrefaction). Now understanding is the most noble effect that takes place in this lower world. Therefore, it is not enough to ascribe it to a remote agent, unless we suppose it to have also a proximate cause. This argument, however, does not avail against Avicenna, because he holds² that any animal can be generated without seed.

Again. The intention of the effect shows the agent. Therefore, animals engendered of putrefaction are not intended by a lower nature but only by a higher, since they are produced by a higher nature only: for which reason Aristotle in Metaphysics 7¹ says that they are effects of chance. In contrast, animals that are produced from seed are intended both by the higher and the lower nature. But this effect—which is to abstract universal forms from the phantasms—is in our intention, and not merely in the intention of the remote agent. Therefore, it follows that in us there must be a proximate principle of such an effect: and this is the active intellect. Therefore, it is not a separate substance, but a power of our soul.

Again. The nature of every mover includes a principle sufficient for its natural operation: and if this operation consists in an action, that nature includes an active principle, as appears in the powers of the nutritive soul of plants; but if this operation is a passion, it includes a passive principle, as appears in the sensitive powers of animals. Now man is the most perfect of all lower movers. And his proper and natural operation is to understand, which is not completed without some passion, insofar as the intellect is passive to the intelligible; nor again without action, insofar as the intellect makes things that are potentially intelligible to be intelligible actually. Therefore, the respective principles of both (namely, the active and possible intellects), must be in man’s nature, and neither of these must be separate from the soul of man as to its being.

Again. If the active intellect be a separate substance, it is evident that it is above man’s nature. Now an operation which man performs by the power alone of a higher substance is a supernatural operation (like the working of miracles, prophesying, and other like things which men do by God’s favor). Since, then, man cannot understand except by the power of the active intellect, if the active intellect be a separate substance, it will follow that intelligence is not a natural operation to man. Consequently, man cannot be defined as being intellectual and rational.

If, however, it be said that these actions are ascribed to man insofar as the aforesaid intellects are in conjunction with us, as Averroes says,¹ it has already been shown² that the possible intellect’s conjunction with us (if it be a separate substance such as he holds it to be) does not suffice for us to understand by its means. The same evidently applies to the active intellect. For the active intellect is to the intelligible species received into the possible intellect, as art to the artificial forms which art produces in matter, as appears from the example given by Aristotle in On the Soul 3.³ Now art-forms do not acquire the action of art, but only a formal likeness, so that neither can the subject of these forms exercise the action of the craftsman. Therefore, neither can man exercise the operation of the active intellect through the intelligible species being made actual in him by the active intellect.

Again. A thing that cannot set about its proper operation unless it be moved by an outward principle is moved to operate rather than moves itself. Hence irrational animals are moved to operate rather than move themselves, since their every operation depends on the outward principle which moves them: for their sense, moved by the outward sensible, makes an impression on their imagination, and thus there is an orderly process in all their powers down to the motive powers. Now man’s proper operation is intelligence, the first principle of which is the active intellect which produces the intelligible species to which the possible intellect is passive in a sense, and this being made actual moves the will. If, then, the active intellect is a substance outside man, all man’s operation depends on an outward principle: consequently, he will not move himself but will be moved by another. Hence he will not be the master of his own operations, nor will he be deserving of praise or blame, and there will be an end to all moral science and political life, which is absurd. Therefore, the active intellect is not a substance separate from man.

That it is not impossible for the possible and active intellect to concur in the one substance of the soul

Perhaps it will seem impossible to someone that one and the same substance (namely, that of our soul) should be in potency to all intelligibles (which belongs to the possible intellect), and should make them actual (which belongs to the active intellect), since a thing does not act as it is in potency, but as it is in act. Therefore, it does not appear that the active and possible intellect can concur in the one substance of the soul.

If, however, one look into the matter rightly, nothing impossible or difficult follows. For nothing hinders one thing from being in one respect in potency with regard to some other thing, and in act in another respect, as we observe in natural things: for air is actually damp and potentially dry, whereas with earth it is the opposite. Now we find this same comparison between the intellective soul and the phantasms. For the soul has something in act to which the phantasm is in potency, and is in potency to something which is found actually in the phantasms. For the substance of the human soul has immateriality, and, as is evident from what has been said,¹ it consequently has an intellectual nature, since such is every immaterial substance. Yet it does not follow that it is likened to this or that determinate thing, which is required in order that our soul may know this or that thing determinately: for all knowledge results from the likeness of the known in the knower. Hence the intellective soul remains itself in potency to the determinate likenesses of things that can be known by us, and these are the natures of sensible things. It is the phantasms that offer us these determinate natures of sensible things: these phantasms, however, have not yet acquired intelligible being—since they are images of sensible things even as to material conditions, which are the individual properties—and, moreover, are in material organs. Therefore, they are not actually intelligible. And yet, since in the individual man whose image the phantasms reflect, it is possible to conceive the universal nature apart from all the individualizing conditions, they are intelligible potentially. Accordingly, they have intelligibility potentially, though they are actually determinate as images of things: but it was the opposite in the intellective soul. Consequently, there is in the intellective soul an active power in respect of the phantasms, rendering them actually intelligible, and this power of the soul is called the active intellect. There is also in the soul a power that is in potency to the determinate images of sensible things, and this is the power of the possible intellect.

Nevertheless, that which is found in the soul differs from what is found in natural agents. For in the latter, one thing is in potency to something according to the same mode as it is actually found in another: for the matter of the air is in potency to the form of water in the same way as it is in water. Hence natural bodies which have a common matter are mutually active and passive in the same order. But the intellective soul is not in potency to the likenesses of things which are in the phantasms, according to the mode in which they are there, but according as these images are raised to something higher by being abstracted from the individualizing conditions of matter, so that they become actually intelligible. Consequently, the action of the active intellect on the phantasm precedes the reception by the possible intellect. And thus the preeminence of the action is ascribed not to the phantasms but to the active intellect. For this reason Aristotle says¹ that it is compared to the possible intellect as art to matter.

We should have a perfect example of this if the eye, besides being a diaphanous body and receptive of colors, had sufficient light to make colors actually visible. This is just as certain animals are said to throw sufficient light on objects by the light of their eyes, for which reason they see more by night and less by day, because their eyes are weak, since they are moved by a dim light, and confused by a strong one. There is something like this in our intellect insofar, as with regard to things most manifest, it is as the eye of the owl with regard to the sun:¹ so that the little intellectual light which is connatural to us is sufficient for our act of intelligence.

It is clear that the intellectual light connatural to our soul suffices to cause the action of the active intellect, if we consider why it is necessary to place an active intellect in the soul. For the soul was found to be in potency to intelligibles, as the senses to sensibles, since just as we do not always sense, so neither do we always understand. Now these intelligibles which the human intellective soul understands were asserted by Plato to be intelligible of themselves, namely ideas: hence it was unnecessary for him to admit an active intelligence in respect of intelligibles. But if this were true, it would follow that the more things are intelligible of themselves, the more would they be understood by us. Yet this is clearly false, because the nearer things are to our senses, the more intelligible are they to us, though in themselves they are less intelligible. Consequently, Aristotle was moved to assert that those things which are intelligible to us are not certain things that are intelligibles in themselves, but that they are made intelligible from sensibles. Hence he had to place a power which would do this; and this is the active intellect. Therefore, the reason for placing the active intellect is that it may make intelligibles proportionate to us. Now this does not exceed the mode of the intellectual light connatural to us. Therefore, nothing hinders us from ascribing the action of the active intellect to the light of our soul, and especially since Aristotle compares the active intellect to a light.¹

That Aristotle’s opinion concerning the active intellect was not that it is a separate substance, but rather that it is part of the soul

Since, however, some agree with the above opinion¹ in the belief that it reflects the mind of Aristotle, we must show from his words that in his opinion the active intellect is not a separate substance.

For he says,¹ in the first place, that just as in every nature there is something like the matter in every genus, which is in potency to all that comes under that genus; while there is also a cause like the efficient cause, as art in relation to matter, so must these differences be in the soul. The latter, that which is as matter in the soul, is the (possible) intellect wherein all things intelligible are made: whereas the former, which is as the efficient cause in the soul, is the intellect by which we make all things (namely, actually intelligible), and this is the active intellect, which is like a habit, and not like a power. In what sense he calls the active intellect a habit, he explains by adding that it is as a light, since in a manner light makes potential colors to be colors actually, that it, insofar as it makes them to be actually visible, because this is what is ascribed to the active intellect in regard to intelligibles.

From this we gather that the active intellect is not a separate substance but rather a part of the soul: for he says explicitly that the possible and active intellect are differences of the soul and that they are in the soul. Therefore, neither of them is a separate substance.

Again. His argument proves this also. Because in every nature in which we find potency and act, there is something by way of matter that is in potency to the things of that genus, and something by way of agent that reduces the potency to act: even as in the products of art, there is art and matter. Now the intellective soul is a nature in which we find potency and act, since sometimes it is actually understanding and sometimes potentially. Therefore, in the nature of the intellective soul, there is something by way of matter that is in potency to all intelligibles, and this is called the possible intellect, and there is something by way of efficient cause which makes all things actual, and is called the active intellect. Consequently, both intellects are in the nature of the soul, according to the argument of Aristotle, and are not something separate as to being from the body of which the soul is the act.

Moreover. Aristotle says that the active intellect is like a habit that is a light. Now a “habit” does not designate something existing by itself, but something belonging to one who has it. Therefore, the active intellect is not a substance existing separately by itself, but is part of the human soul.

The text of Aristotle, however, does not mean that the effect of the active intellect may be described as a habit, as though the sense were that the active intellect makes man to understand all things, which is like a habit. For the meaning of habit, as the commentator Averroes says on this passage, is that he who has the habit understands by that which is proper to him, by himself, and whenever he will, without any need in him of something extrinsic, since he explicitly likens to a habit, not the effect itself, but the intellect by which we make all things.

And yet we are not to understand that the active intellect is a habit in the same way as a habit is in the second species of quality, in which sense some have said that the active intellect is the habit of principles. Because this habit of principles is derived from sensibles, as Aristotle proves in Posterior Analytics 2.¹ Consequently, it must be the effect of the active intellect, to which it belongs to make actually intelligible the phantasms that are understood potentially. But habit is to be taken as contrasted with privation and potency, in which sense every form and act may be called a habit. This is evident since he asserts that the active intellect is a habit in the same way as light is a habit.

After this he adds that this intellect, namely the active, is separate, unmixed, impassible, and an actually existing substance. Now of these four conditions which he ascribes to the active intellect, he had already¹ explicitly ascribed two to the possible intellect, namely, that it is unmixed and separate. He had applied the third² (namely, that it is impassible) with a distinction; for he proves in the first place that it is not passible as the senses are, and afterwards he shows that, taking passion broadly, it is passive insofar as it is in potency to intelligibles. But as to the fourth, he absolutely denies it of the possible intellect, and says that it was in potency to intelligibles, and none of these things was actual before the act of intelligence.³ Accordingly, in the first two the possible intellect agrees with the active; in the third it agrees partly, and partly differs; while in the fourth the active differs altogether from the possible intellect. He proves these four conditions of the active intellect by one argument, when he goes on to say: for the agent is always more noble than the patient, and the (active) principle than matter.⁴ For he had said above that the active intellect is like an efficient cause, and the possible intellect like matter. Now by this middle proposition the two first conditions are proved thus. The agent is more noble than the patient and matter. But the possible intellect, which is as patient and matter, is separate and unmixed, as proved above. Much more, therefore, is the agent. The others are proved by this middle proposition thus: the agent is more noble than the patient and matter, in that it is compared to it as agent and actual being to patient and potential being. Now, the possible intellect is, in a sense, patient and potential being. Therefore, the active intellect is a non-passive agent and an actual being. And it is evident that neither from these words of Aristotle can we gather that the active intellect is a separate substance, but that it is separate in the same sense as he had already said of the possible intellect—namely, as not having an organ. When he says that it is an actually existing substance, this is not inconsistent with the substance of the soul being in potency, as we have shown above.⁵

Then he goes on to say: now knowledge, when actual, is identical with the thing.¹ On this, the Commentator says that the active intellect differs from the possible because that which understands and that which is understood are the same in the active intellect, but not in the possible. But this is clearly contrary to the meaning of Aristotle. For he had employed the same words before in speaking of the possible intellect, where he says of the possible intellect that it is intelligible as intelligibles are, since in things void of matter, understanding and that which is understood are the same, because speculative knowledge is identified with that which it speculates.² For he clearly wishes to show that the possible intellect is understood like other intelligibles from the fact that the possible intellect, as understanding actually, is the same as that which is understood. Moreover, he had said a little earlier that, in a manner, the possible intellect is potentially the intelligibles, but is nothing actually before it understands,³ where he clearly gives one to understand that by understanding actually it becomes the intelligibles. Nor is it surprising that he should say this of the possible intellect, since he had already⁴ said this of sense and the sensible in act. For the sense becomes actual by the species actually sensed; and in like manner the possible intellect becomes actual by the intelligible species in act; and for this reason the intellect in act is said to be the intelligible itself in act. Accordingly, we must say that Aristotle, after defining the possible and active intellects, begins here to describe the intellect in act, when he says that actual knowledge is the same as the thing actually known.

Afterwards, he says: but that which is in potency, in point of time, precedes in one subject, but not altogether in point of time.¹ Which distinction between potency and act is employed by him in several places, namely, that act is naturally prior to potency, but that in point of time, potency precedes act in one and the same subject that is changed from potency to act; yet, absolutely speaking, potency does not precede act even in point of time, since potency is not reduced to act except by an act. He says, therefore, that the intellect which is in potency (namely, the possible intellect considered as being in potency) is prior in time to the intellect in act, and this I say is in one and the same subject. But not altogether, that is, universally, because the possible intellect is reduced to act by the active intellect, which again is in act, as he said, by some possible intellect made actual. Therefore, he said² that before learning a man needs a teacher to reduce him from potency to act. Accordingly, in these words he shows the relation of the possible intellect, as in potency, to the intellect in act.

Then he says: but it does not sometimes understand and sometimes not understand.¹ In this he indicates the difference between the intellect in act and the possible intellect. For he said above² of the possible intellect that it does not understand always, but sometimes does not understand, when it is in potency to intelligibles, and sometimes understands, namely, when it is them actually. Now the intellect becomes actual by becoming the intelligibles, as he had already stated. Consequently, it is not competent to it to understand sometimes, and sometimes not to understand.

Afterwards he adds: but that alone is separate which is truly (intellect). This cannot apply to the active intellect, since it alone is not separate, for he had already said the same of the possible intellect. Nor can it apply to the possible intellect, since he had already said this of the active intellect. It follows, then, that it is said of that which includes both, namely, the intellect in act, of which he was speaking, because this alone in our soul is separate and uses no organ, which belongs to the intellect in act (namely, that part of the soul by which we understand actually and which includes both the possible and active intellect). Therefore, he adds that only this part of the soul is immortal and everlasting, as being independent of the body through being separate from it.

The human soul

That the human soul is not corrupted when the body is corrupted

From the foregoing, then, we can clearly show that the human soul is not corrupted when the body is corrupted.

For it was proved above¹ that every intellectual substance is incorruptible. Now man’s soul is an intellectual substance, as we have proved.² Therefore, it follows that the human soul is incorruptible.

Again. Nothing is corrupted on account of that in which its perfection consists: for these changes are contrary to one another (namely, those which tend to perfection and corruption). Now the perfection of the human soul consists in a certain abstraction from the body: for the soul is perfected by knowledge and virtue; and as to knowledge it is perfected the more it considers immaterial things, while the perfection of virtue consists in man not following the passions of the body, but tempering and curbing them according to reason. Therefore, the soul is not corrupted through being separated from the body.

If, however, it be said that the soul’s perfection consists in its being separated from the body as regards operation, and its corruption in its being separated as regards being, this reply is not to the point. Because a thing’s operation points to its substance and being, since a thing acts according as it is a being, and a thing’s proper operation follows its proper nature. Therefore, the operation of a thing cannot be perfected except insofar as that thing’s substance is perfected. Hence if the soul is perfected in quitting the body as to its operation, its incorporeal substance will not fail in its being through being separated from the body.

Again. That which properly perfects man in his soul is something incorruptible. For the proper operation of man, as man, is to understand, since it is in this that he differs from brutes, plants, and inanimate things. Now the object of the act of understanding is properly the universal and the incorruptible as such, and perfection should be proportionate to the perfectible. Therefore, the human soul is incorruptible.

Moreover. The natural appetite cannot possibly be frustrated. Now man naturally desires to exist always: this is evidenced by the fact that being is that which all things desire, and man by his intellect apprehends being not merely as now, as dumb animals do, but simply.¹ Therefore, man acquires perpetuity in regard to his soul, which apprehends being simply and for all time.

Again. Whatever is received in a thing is received in it according to the mode of that in which it is. Now the forms of things are received in the possible intellect according as they are actually intelligible. And they are actually intelligible according as they are immaterial, universal, and consequently incorruptible. Therefore, the possible intellect is incorruptible. But, as we proved above,¹ the possible intellect is part of the human soul. Therefore, the human soul is incorruptible.

Again. Intelligible being is more lasting than sensible being. Now in sensible things that which is by way of first recipient (namely, prime matter) is incorruptible as to its substance. Much more so, therefore, is the possible intellect, which is the recipient of intelligible forms. Therefore, the human soul also, of which the intellect is a part, is incorruptible.

Moreover. The maker is more noble than the thing made, as Aristotle also says.¹ But the active intellect makes things actually intelligible, as shown above.² Since, then, things actually intelligible, as such, are incorruptible, much more will the active intellect be incorruptible. Therefore, such is also the soul, the light of which is the active intellect, as appears from what has been already stated.³

Again. No form is corrupted except either by the action of its contrary, or by the corruption of its subject, or by the failing of its cause: by the action of its contrary, as heat is destroyed by the action of cold; by the corruption of its subject, as the faculty of sight is destroyed through the destruction of the eye; and by the failing of its cause, as the light of the air fails through the sun (which was its cause) failing to be present. But the human soul cannot be destroyed by the action of a contrary, for nothing is contrary to it since by the possible intellect it is cognizant and receptive of all contraries. Likewise, it cannot be corrupted through the corruption of its subject, for it has been proved above¹ that the human soul is a form independent of the body as to its being. Moreover, it cannot be destroyed through the failing of its cause, since it can have none but an eternal cause, as we shall show further on.² Therefore, the human soul can in no way be corrupted.

Again. If the soul be corrupted through the corruption of the body, it follows that its being is weakened through the body being weakened. Now if a power of the soul is weakened through the weakening of the body, this is only accidental, namely, insofar as the power of the soul needs a bodily organ. Thus the sight is weakened only accidentally through the weakening of the organ. This is made clear as follows. If some weakness were essentially attached to the power, the latter would never be repaired through the organ being repaired. Yet we see that however much the power of sight may seem to be weakened, if the organ be repaired, the sight is repaired: therefore, Aristotle says in On the Soul 1 that if an old man were to be given the eye of a young man, he would certainly see as well as a young man does.¹ Accordingly, since the intellect is a power of the soul that needs no organ, as shown above,² it is not weakened, either essentially or accidentally, by old age or any other bodily weakness. If, on the other hand, the operation of the intellect happen to be affected by fatigue or some hindrance on account of the weakness of the body, this is owing not to weakness of the intellect itself, but to the weakness of the powers which the intellect needs—namely, of the imagination, memory, and cogitative power. It is therefore clear that the intellect is incorruptible. Consequently, the human soul is also, since it is an intellective substance.

This is also proved from the authority of Aristotle. For he says in On the Soul 1 that the intellect is clearly a substance and incorruptible:¹ and it may be gathered from what has been already said² that this cannot refer to a separate substance that is either the possible or the active intellect.

It is also clear from the foregoing words of Aristotle that, although he states the soul to be a form, he does not assert it to be non-subsistent and therefore corruptible, as Gregory of Nyssa¹ would have him mean, since he excludes the intellective soul from the generality of other forms by saying that it remains after the soul, and that it is a substance.

The teaching of the Catholic faith is in keeping with the foregoing. For it is said in the book De ecclesiasticis dogmatibus, 16: We believe that man alone has a subsistent soul which survives even after it has put off the body, and is the life-giving source of the senses and faculties; neither does it die when the body dies, as the Arabian asserts, nor after a short interval of time, as Zeno pretends, because it is a living substance.

By this is set aside the error of the ungodly, in whose person Solomon says: we were born of nothing, and hereafter we shall be as though we had never been (Wis 2:2); and in whose person Solomon says: the fate of the sons of men and the fate of beasts is the same; as man dies, so dies the other. They all have the same breath, and man has no advantage over the beasts (Eccl 3:19). For it is clear that he speaks not in his own person but in that of the ungodly, since at the end of the book he says as though deciding the point: the dust returns to the earth as it was, and the spirit returns to God who gave it (Eccl 12:6–7).

Moreover, there are innumerable passages of Sacred Scripture that declare the immortality of the soul.

Arguments to prove that the soul is corrupted when the body is corrupted

Certain arguments would seem to show that human souls cannot possibly remain after the body.

For if human souls are multiplied according to the multiplication of bodies, as we have proved above,¹ it follows that when the bodies are destroyed, the souls cannot remain in their multitude. Therefore, one of two alternatives must follow: either that the human soul altogether ceases to exist, or that only one remains. And this would seem to concur with the opinion of those who state that only that which is one in all men is incorruptible, whether this be the active intellect alone, as Alexander says, or the possible besides the active intellect, according to Averroes.²

Moreover. The formal ratio is the cause of specific difference. Now, if many souls remain after the corruption of bodies, they must differ from each other, because as there is identity where there is oneness of substance, so is there difference where there are many in substance. But in souls that survive bodies there can be no difference other than formal, since they are not composed of matter and form, as we have proved above¹ of every intellectual substance. Hence it follows that they differ specifically. And yet souls are not changed to another species by the corruption of the body, since whatever is changed from species to species is corrupted. It follows, therefore, that even before they were separated from their bodies, they were different in species. Now composites derive their species from their form. Consequently, individual men will differ specifically. Which is absurd. Therefore, it is seemingly impossible that many souls should survive their bodies.

Again. According to those who hold the eternity of the world, it would seem altogether impossible to maintain that human souls remain in their multitude after the death of the body. For if the world exists from eternity, movement is from eternity; consequently, generation also is eternal. But if generation be eternal, an infinite number of men have died before us. Consequently, if the souls of the dead remain in their multitude after death, we must say that there is actually an infinite number of souls of men already dead. But this is impossible, since the actually infinite cannot exist in nature. Therefore, it follows that souls do not remain many after death if the world is eternal.

Again. That which accrues to a thing and departs from it without the latter being corrupted accrues to it accidentally,¹ or this is the definition of an accident. Hence if the soul be not corrupted when parted from the body, it would follow that the soul is united to the body accidentally. Consequently, man is an accidental being, composed of soul and body. And it will follow, moreover, that there is no human species, since one species does not result from things united accidentally, for “white man” is not a species.

Moreover. There cannot possibly be a substance that has no operation. Now all operation of the soul ends with the body, which is proved by induction. For the nutritive powers of the soul operate through the bodily qualities, and through a bodily instrument, and act on the body, which, perfected by the soul, is nourished and increased, and from which is determined the seed for generation. Again, all the operations of the powers belonging to the sensitive soul are accomplished through bodily organs, some of them being accomplished with a certain bodily transmutation (for instance, those which are called passions of the soul, such as love, joy, and the like). Moreover, though understanding is not an operation fulfilled through a bodily organ, yet its objects are the phantasms which stand in relation to it, as colors to the sight.¹ Therefore, as the sight cannot see without colors, so the intellective soul cannot understand without phantasms. Further, the soul, in order to understand, needs the powers which prepare the phantasms so as to make them actually intelligible (namely, the cogitative power and the memory); which clearly cannot remain after the body, since they are acts of certain organs of the body, and operate through those organs. Hence Aristotle says that the soul does not understand without phantasms,² and that it understands nothing without the passive intellect,³ which he calls the cogitative power, and which is corruptible. For this reason he says that man’s act of understanding is corrupted when something within him is corrupted,⁴ namely, the phantasm or the passive intellect. And it is stated in On the Soul 3⁵ that after death we do not remember what we knew in life. It is accordingly evident that no operation of the soul can remain after death. Therefore, neither does its substance remain, since no substance can be without operation.

Continuation of the foregoing

Now, since these arguments lead to a false conclusion, as was shown above,¹ we must endeavor to answer them.

And, in the first place, it must be observed that whatever things have to be adapted and proportionate to one another are together multiplied or unified, each by its own cause. Therefore, if the being of one depends on the other, its unity or multiplicity depends also on it; otherwise it depends on some other extrinsic cause. Now form and matter need always to be mutually proportionate and naturally adapted, so to speak, because the proper act is produced in its proper matter. Consequently, matter and form must always agree in point of multitude and unity. Hence if the being of the form depend on matter, its multiplication, as also its unity, depends on matter. But if not, the form must be multiplied according to the multiplication of the matter, that is, together with matter and in proportion to it, yet not so that the unity or multiplicity of the very form depend on matter. Now it has been shown¹ that the human soul is a form independent of matter as to its being. Therefore, it follows that souls are indeed multiplied according as bodies are multiplied, and yet the multiplication of bodies is not the cause of the multiplication of souls. Therefore, it does not follow that the plurality of souls ceases with the destruction of bodies, as the first argument concluded.

From this the reply also to the second argument is clear. For it is not every difference of forms that causes a difference of species, but only that which is in respect of formal principles, or of a different kind of form, since it is clear that the form is essentially distinct in this and that fire, and yet neither fire nor form is specifically different. Accordingly, multitude of souls separated from their bodies results from the substantial distinction of forms, since one soul is substantially distinct from another; and yet this distinction does not result from a distinction in the essential principles of the soul, nor from a different kind of soul, but from the various coaptation of souls to bodies, because this soul is adapted to this and not to that body, and that soul to another body, and so on. And this coaptation remains in the soul even after the body has perished, even as the soul’s substance remains through being independent of the body in the point of being. For the soul is the form of the body according to its substance: or else it would be united to the body accidentally, and consequently the union of body and soul would result in one thing not essentially, but accidentally. Now it is as forms that souls need to be adapted to their bodies. Therefore, it is clear that these same various coaptations remain in separated souls; and consequently, the plurality of souls remains also.

The third argument given above has been the occasion for some who held the world to be eternal to fall into various strange opinions. For some granted the conclusion absolutely, and said that human souls perish altogether with their bodies. Others said that of all souls there remains some one thing separate that is common to all, namely, the active intellect according to some, or besides this the possible intellect, according to others. Others, however, held that souls remain in their multitude after bodies, but lest they should be compelled to admit an infinite number of souls, they said that the same souls are united to different bodies after a certain time. This was the Platonists” opinion, of which we shall treat further on.¹ Others again, avoiding all the above statements, said that it is not impossible for separate souls to be actually infinite in number. Because in things not ordered to each other to be actually infinite is to be infinite accidentally, and they hold that there is no reason not to admit this. This is the opinion of Avicenna and Algazel. We do not find it expressly stated by Aristotle to which of these opinions he adhered, although he holds explicitly the eternity of the world. The last of the above opinions, however, is not inconsistent with the principles laid down by him. For in Physics 3² and On Heaven and Earth 1,³ he proves that the actually infinite is impossible in natural bodies, but not in immaterial substances. Nevertheless, it is certain that this question offers no difficulty to those who profess the Catholic faith, since they do not admit the world to be eternal.

Again, if the soul remain after the destruction of the body, it does not follow that it must have been accidentally united to it, as the fourth argument concluded. For an accident is described as that which may be present or absent without the corruption of the subject composed of matter and form. Now, if this be referred to the principles of the composite subject, it is found to be untrue. For it is clear that prime matter is not subject to generation and corruption, as Aristotle proves in Physics 1.¹ Therefore, it remains in its essence when the form departs. And yet the form was united to it not accidentally but essentially, since it was united to it in one being. Likewise, the soul is united to the body in one being, as we proved above.² Therefore, though it survives the body, it is united to it essentially and not accidentally. That prime matter does not remain actually after the form except in respect of the act of another form, but the human soul remains in the same act, is due to the fact that the human soul is form and act, whereas prime matter is a being in potency.

As to the statement put forward in the fifth argument—that no operation can remain in the soul when separated from the body—we say that it is false, since those operations remain which are not exercised through organs. Such are to understand and to will. But those operations do not remain which are performed through bodily organs, such as the operations of the nutritive and sensitive powers.

It must be observed, however, that the soul understands in a different way when separated from the body and when united to it, even as it has a different mode of existence, because a thing acts according as it is. For although the being of the soul while united to the body is absolute and independent of the body, nevertheless the body is like its lodging and the subject that receives it. Therefore in consequence, its proper operation, which is to understand, has its object in the body (namely, the phantasms), though not depending on the body as though it were performed through a bodily organ. Hence, as long as the soul is in the body, it cannot understand without a phantasm; neither can it remember except through the powers of cogitation and memory, by which the phantasms are prepared, as stated above.¹ For this reason understanding, as regards this mode, is destroyed when the body perishes, as is remembering. On the other hand, the separated soul has its being apart from the body. Therefore, neither will its operation (which is to understand) be performed in dependence upon certain objects existing in bodily organs, which are the phantasms; but it will understand by itself after the manner of substances wholly separate from bodies as to their being, of which we shall speak further on.² From which substances, moreover, it will be able to receive a more abundant inflow as from things higher than itself, so as to understand more perfectly. We have a sign of this in the young.³ For the soul, the more it is withdrawn from being occupied about its own body, is rendered more apt to understand certain higher things: therefore, the virtue of temperance, which withdraws the soul from bodily pleasures, above all makes men apt in understanding. Moreover, men while asleep and not using their bodily senses, and when there is no disturbance of the humors or vapours to hinder them, are influenced by higher beings so as to perceive certain future things that surpass the purview of human reasoning. This is much more the case with those who are in a faint or an ecstasy, insofar as they are the more withdrawn from the senses of the body. Nor does this happen unreasonably, because, since the human soul, as shown above,⁴ is on the boundary line of corporeal and incorporeal substances (as though it were on the horizon of eternity and time) approaches to the higher world by withdrawing from the lower. Therefore, when it shall be wholly separated from the body, it will be perfectly likened to separate substances as to the manner of understanding and will receive their influence abundantly.

Accordingly, though our act of understanding as regards its mode in the present life ceases when the body perishes, another and higher mode of understanding will take its place.

Remembrance, however, since it is an act performed through a bodily organ, as Aristotle proves in On Memory and Recollection,¹ it cannot remain in the soul after the body unless remembrance be taken equivocally for the understanding of those things which the soul knew before: for the soul must remember what it knew in life, since the intelligible species are received indelibly into the possible intellect, as we have shown above.²

With regard to the other operations of the soul, such as to love, to rejoice, and the like, we must beware of equivocation. For sometimes they are taken for passions of the soul: and thus they are acts of the sensible appetite in respect of the irascible and concupiscible faculties, together with a certain bodily transmutation. And thus they cannot remain in the soul after death, as Aristotle proves in his book On the Soul.¹ But sometimes they are taken for a simple act of the will that is without passion. Therefore, Aristotle says in Ethics 7 that God rejoices by one simple operation,² and in 10 Ethics that in the contemplation of wisdom there is wonderful pleasure,³ and in Ethics 8 he distinguishes the love of friendship from the love that is a passion.⁴ Now, since the will is a power that uses no organ, as neither does the intellect, it is clear that these things, insofar as they are acts of the will, remain in the separated soul.⁵

Hence it cannot be concluded from the foregoing arguments that man’s soul is mortal.

That the souls of dumb animals are not immortal

From what has been said it may be clearly proved that the souls of dumb animals are not immortal.

For it has been already shown.¹ that no operation of the sensitive part can possibly be without the body. Now we cannot find in the souls of dumb animals any operation superior to those of the sensitive part, for they neither understand nor reason. This appears from the fact that all animals of the same species operate in the same way, as though moved by nature and not as operating by art: thus every swallow builds its nest, and every spider spins its web, in the same way.² Therefore, the souls of dumb animals have no operation that is possible without the body. Since, then, every substance has some operation, the soul of a dumb animal cannot exist apart from the body. Therefore, it perishes when the body perishes.

Again. Every form that is separate from matter is actually understood: for the active intellect makes species to be actually intelligible, insofar as it abstracts them, as appears from what has been said.¹ But, if the dumb animal’s soul remains after its body has perished, it will be a form separate from matter. Therefore, it will be a form actually understood. Now, in things separate from matter, that which understands is the same as that which is understood, as Aristotle says in On the Soul 3.² Therefore, the soul of a dumb animal, if it survive the body, will be intellectual, which is impossible.

Again. In everything that is able to attain to a certain perfection we find a natural desire for that perfection, since good is what all desire,¹ yet so that each thing desires the good proper to it.² Now, in dumb animals we do not find a natural desire for perpetual existence except as regards perpetuity of species, inasmuch as we find in them the desire for begetting whereby the species is perpetuated. This desire is found in both plants and inanimate things, but not as regards the appetite that is proper to an animal as such, which appetite is consequent upon apprehension. For, since the sensitive soul does not apprehend except here and now, it cannot possibly apprehend perpetual existence. Neither, therefore, does it desire it with animal appetite. Therefore, the soul of a dumb animal is not capable of perpetual existence.

Moreover. Since pleasures perfect operations, as Aristotle says in 10 Ethics,¹ the operation of a thing is directed to that in which it takes pleasure as in an end. Now all pleasures of dumb animals are referred to the preservation of the body: for they delight not in sounds, perfumes, and sights, except insofar as they are indicative of foods or venereal matters, which are the objects of all their pleasures. Hence all their operations are directed to the preservation of their bodily existence as their end. Therefore, they have no existence apart from the body.

The teaching of the Catholic faith is in keeping with this statement. For it is said of the dumb animal’s soul: its¹ life is in the blood (Gen 9:4),² as though to say: Its existence depends on the blood remaining. It is also said in the book De ecclesiasticis dogmatibus:³ we declare that man alone has a subsistent soul, that is, which has life of itself: and that the souls of dumb animals perish with the body.

Moreover, Aristotle says in On the Soul 2 that the intellective part of the soul is distinguished from the other parts as incorruptible from corruptible.¹

This excludes the opinion of Plato¹ who held that the souls even of dumb animals are immortal.

And yet it would seem possible to prove that the souls of dumb animals are immortal. For if a thing has an essential operation belonging to itself, it is also self-subsistent. Now the sensitive soul in dumb animals has an essential operation in which the body has no part, namely, to move, because a mover is composed of two parts, one of which is mover and the other moved.¹ Therefore, since the body is something moved, it follows that the soul alone is mover; therefore, it is self-subsistent. Consequently, it cannot be corrupted accidentally when the body perishes, since those things alone are corrupted accidentally which do not have essential being. Nor can it be corrupted essentially, seeing that it has no contrary, nor is it composed of contraries. It follows, therefore, that it is altogether incorruptible.

The argument of Plato,¹ by which he proved that every soul is immortal, would seem to come to the same as this, namely, the soul moves itself, and whatever moves itself must be immortal. For the body does not die except when it is abandoned by that which moved it, and a thing cannot abandon itself. Consequently, according to him, that which moves itself cannot die. And so he concluded that every moving soul, even that of dumb animals, is immortal. We have said that this argument comes to the same as the preceding, because, since in Plato’s opinion nothing moves unless it be moved, that which moves itself is an essential mover, and therefore has an essential operation.

Again, Plato held that the sensitive soul has an operation of its own not only in moving, but also in sensing.¹ For he declared that sensation is a movement of the soul itself which senses: and that the soul, being moved thus, moved the body to sensation.² Therefore, when he defined sense, he said that it is the movement of the soul through the body.³

Now it is clear that these statements are false. For to sense is not to move, but to be moved, because from being potentially sentient, the animal is made actually sentient through the sensible objects by which the senses are impressed. But it cannot be said that the sense is passive to the sensible in the same way as the intellect is passive to the intelligible object, so that sensation could be an operation of the soul without a bodily instrument in the same way as understanding is. For the intellect apprehends things as abstracted from matter and material conditions, which are the principles of individuality, but the sense does not. This is evidenced by the sense being confined to particular objects, while understanding is of universals. It is therefore clear that the senses are passive to things as existing in matter, while the intellect is not, but according as they are subject to abstraction. Therefore, the passion of the intellect is without corporeal matter, but the passion of the senses is not.

Again. Different senses are receptive of different sensibles: for instance, sight of colors, hearing of sounds. Now this difference clearly arises from the different dispositions of the organs, for the organ of sight needs to be in potency to all colors, and the organ of hearing to all sounds. But if this reception took place without any corporeal organ, the same faculty would be receptive of all sensible objects, since an immaterial power, for its own part, stands in an equal relation to all such qualities. Therefore, the intellect, through not using a corporeal organ, takes cognizance of all sensible objects. Therefore, there is no sensation without a corporeal organ.

Plato’s statement that a soul moves itself may seem to be well founded by reason of what we observe in regard to bodies. For it seems that no body moves unless it is moved: hence Plato said that every mover is moved. And since we cannot go on to infinity, as though every thing moved were moved by another, he stated that in each order the first mover moved itself. From this, it followed that the soul, which is the first mover in the movement of animals, is something that moves itself.

But this is shown to be false, on two counts. First, because it has been proved¹ that whatever is moved of itself is a body: therefore, since a soul is not a body, it is impossible for it to be moved save accidentally.

Second, because since a mover as such is in act, while the thing moved as such is in potency, and since nothing can be in act and potency in the same respect, it will be impossible for the same thing to be mover and moved in the same respect. But if a thing is stated to move itself, one part of it must be mover and the other part moved. It is in this way that an animal is said to move itself, because the soul is mover and the body moved. Since, however, Plato did not hold that the soul is a body, although he made use of the word “movement” which belongs to bodies properly speaking, he did not mean movement in this strict sense, but referred it in a more general way to any operation. In this sense Aristotle also says that sensation and understanding are movements: but in this way movement is the act not of that which is in potency but of that which is perfect.¹ Consequently, when he said that the soul moves itself, by this he meant to say that it acts without the help of the body, whereas it is the other way about with other forms which exercise no action apart from matter: for that which heats is not heat by itself but something hot. Hence he wished to conclude that every soul which causes movement is immortal: because that which has an essential operation must also have essential existence.

But it has been already proved that the operation of the soul of a dumb animal (namely, sensation) cannot be without the body. And this is much more evident as regards its operation of appetite. Because all things pertaining to the appetite of the sensitive faculty are manifestly accompanied by a certain bodily transmutation, and are known as passions of the soul.

From this it follows that not even is movement an operation of the sensitive part without an organ. For the soul of a dumb animal does not move except through sense and appetite, because the power which is said to execute movement makes the members obedient to the command of the appetite. Hence the body is perfected with powers directed to its being moved rather than with powers of moving.

It is accordingly clear that no operation of the dumb animal’s soul can be independent of the body. From this we necessarily conclude that the dumb animal’s soul perishes with the body.

That the human soul begins to exist with the body

Since, however, the same things are found to have both a beginning of being and an end of being, it may seem to some one that, since the human soul has no end of its being, neither has it had any beginning of being, but always has been. And seemingly this can be proved by the following arguments.

For that which will never cease to be has the power to be always. And that which has the power to be always can never be truly said not to be, since a thing’s duration in existence extends as far as its power to exist. Now of everything that has begun to be it, is at some time true to say that it is not. Therefore, that which will never cease to be at no time begins to be.

Further. The truth of intelligibles is not only incorruptible, but is eternal for its own part, because it is necessary, and whatever is necessary is eternal, since not to be is an impossibility for that which necessarily is. Now it is from the incorruptibility of intelligible truth that the soul is proved to have incorruptible being.¹ Therefore, by similar reasoning, from its eternity we can prove the eternity of the soul.

Moreover. A thing is not perfect if it lack several of its principal parts. Now it is clear that the principal parts of the universe are intellectual substances, to which genus human souls belong, as shown above.¹ Consequently, if every day as many human souls begin to exist as men are born, it is evident that many of its principal parts are added to the universe every day, and that it lacks many such parts. Therefore, it follows that the universe is imperfect: which is impossible.

Furthermore, some argue from the authority of Sacred Scripture. For it is stated that on the seventh day God finished his work which he had done, and he rested from all his work which he had done (Gen 2:2). But this would not be so, if he made new souls every day. Therefore, new human souls do not begin to exist, but they have existed from the beginning of the world.

For these and like reasons some, supposing the world to be eternal, have said that as the human soul is incorruptible, so has it existed from eternity. Hence those, namely the Platonists, who maintained that human souls in their multitude are immortal, held that they have also existed from eternity, and are united to bodies at one time, at another separated from them, this vicissitude depending on certain fixed periods of years.¹ On the other hand, those who maintained that human souls are immortal in respect of some one thing which remains over from all men after death held that this same one thing has existed from eternity; whether it be the active intellect alone, as Alexander said, or, besides this, the passive intellect, as Averroes asserted.² Also, this is apparently the meaning of Aristotle’s words, since, speaking of the intellect, he says that it is not only incorruptible, but also perpetual.³

Some, however, professing the Catholic faith, yet imbued with the teachings of the Platonists, have held a middle course. For, since, according to the Catholic faith, nothing is eternal besides God, they maintained not that human souls are eternal, but that they were created with or rather before the visible world, and yet are united anew to bodies. Of those who professed the Christian faith Origen was the first to hold this opinion,¹ and afterwards several followed him. In fact, this opinion survives to this day among heretics, of whom the Manicheans agree with Plato in asserting the eternity and transmigration of souls.

But it can be easily proved that the foregoing opinions are not founded upon truth. For we have already shown above¹ that there is not but one possible or active intellect for all. Hence it remains for us to proceed against those opinions which state that there are many human souls, but that they existed before bodies, either from eternity or from the formation of the world. This would seem unreasonable for the following reasons.

For it was shown above¹ that the soul is united to the body as its form and act. Now although act is naturally prior to potency, yet in one and the same subject it is posterior to it in time, since a thing is moved from potency to act. Therefore, the potentially living² seed precedes the soul which is the act of life.

Again. It is natural to every form to be united to its proper matter. Otherwise, that which is made of form and matter would be something beside nature. Now that which is becoming to a thing according to nature is ascribed to it before that which is becoming to it beside nature, since what becomes a thing beside nature is in that thing accidentally, whereas what is becoming to it according to nature is in it essentially, and that which is accidental always comes after that which is essential.¹ Therefore, it is becoming to the soul to be united to the body before being separated from the body. Therefore, it was not created before the body to which it is united.

Moreover. Every part that is separated from its whole is imperfect. Now since the soul is a form, as proved above,¹ is a part it is a part of the human species. Consequently, as long as it exists by itself apart from the body, it is imperfect. But the perfect precedes the imperfect in the order of natural things. Therefore, it is not becoming to the order of nature that the soul should have been created apart from the body before being united to the body.

Moreover. If souls were created without their bodies, we must inquire how they came to be united to those bodies. For this was either by force or by nature. If by force, it follows that the union of soul and body is unnatural, since whatever is the result of force is against nature. Therefore man, who is composed of both, is something unnatural, and this is clearly false. Moreover, intellectual substances are of a higher order than heavenly bodies. Now nothing violent or contrary is to be found in heavenly bodies. Much less, therefore, is there in intellectual substances.

On the other hand, if souls are united to bodies naturally, it follows that as soon as they were created, souls had a natural desire to be united to bodies. Now the natural appetite is immediately brought into act unless there be an obstacle (as instanced in the movement of heavy and light bodies), for nature always works in the same way. Consequently, from the very moment of their creation they would have been united to bodies unless there were something to prevent it. But everything that hinders the realization of the natural appetite does violence to it. Therefore, it was by violence that at some time souls were separate from bodies. Now this is unreasonable: both because in such substances there can be nothing violent, as we have proved; and because the violent and the unnatural, since they are accidental, cannot precede that which is according to nature, nor can they be consequent upon the whole species.

If, however, it be said that both are natural to the soul (namely, union with the body and separation from the body) according to different times, this seems to be impossible. Because changes that occur naturally in a subject are accidental, such as youth and old age. Hence if union with and separation from the body are natural changes as regards the soul, union with the body will be an accident of the soul: and consequently the man resulting from this union will not be a being in himself, but an accidental being.

If, however, it be said that they are united to bodies neither by violence nor by nature, but by deliberate choice: this is impossible. For no one wishes to come to a worse state except he be deceived. Now the separate soul is of a higher state than when united to the body, especially according to the Platonists, who say that through being united to the body it forgets what it knew before and is balked in the pure contemplation of truth. Therefore, it is not willingly united to the body except it be deceived. But there cannot be any cause of deception in the soul, since according to them it is supposed to have all knowledge. Nor can it be said that its judgment in a particular matter of choice, proceeding from its universal knowledge, is upset on account of the passions, as happens in the incontinent. Passions of this kind are not without a bodily alteration, so that they cannot be in the separate soul. It remains, therefore, that if the soul existed before the body, it would not be united to the body of its own will.

And again, if it be said that the soul is united to the body not from nature, nor of its own will, but by divine ordinance, this also seems inadmissible if souls were created before bodies. For God fashioned each thing according to a manner becoming its nature: hence it is said of each creature, God seeing¹ that it was good (Gen 1:4), and of all together: God saw everything that he had made, and it was very good (Gen 1:31). Consequently, if he created souls separate from bodies, we must say that this manner of being is more becoming their nature. Now, it is not in keeping with the ordinance of the divine goodness to bring things down to a lower state, but rather to raise them to a better. Therefore, it could not have been by divine ordinance that the soul was united to the body.

Origen took note of this, and since he maintained that human souls were created from the beginning, he said that they were united to bodies by divine ordinance, but as a punishment. For he was of opinion that they had sinned before bodies were formed, and that according to the gravity of their sin they were enclosed in bodies more or less noble as in so many prisons.

But this opinion cannot stand. For punishment is something contrary to a good of nature, and for this reason is said to be evil. If, therefore, the union of soul and body is something penal, it is not a good of nature. Yet this is impossible: for it is intended by nature, since it is the end of natural generation. Moreover, it would follow that to be a man is not good according to nature. But nevertheless it is said after the creation of man: God saw everything that he had made, and it was very good (Gen 1:31).

This is also clearly opposed to the teaching of the Apostle. For it is said of Jacob and Esau, that when they were not yet born and had done nothing either good or bad . . . it was said that the elder will serve the younger (Rom 9:11–12). Therefore, before this was said, their souls had not committed any sin: and yet this was said after their conception, as appears from Gen 25:23.

When we were treating of the distinction of things,¹ we adduced against the position of Origen several arguments, which may also be employed here. Therefore, omitting them, let us pass on to others.

Again. We must admit that the human soul either needs the senses, or not. Now experience would seem to make it clear that it needs the senses, because whoever lacks a certain sense has no knowledge of the sensibles that are known through that sense. Thus one born blind has neither knowledge nor any understanding whatever of colors. Moreover, if the soul does not need the senses in order to understand, we should not find in man any relation between sensitive and intellective knowledge. Yet we observe the contrary: for sensation leads to memories, and these lead us to take observation of things, whereby we arrive at the understanding of the universal principles of sciences and arts.¹ Accordingly, if the human soul needs the senses in order to understand, the human soul must not have been fashioned² without the necessary assistance of the senses, since nature fails no thing in what is necessary for the accomplishment of its proper operation—thus it supplies with fitting organs of sense and movement those animals which are animated with the powers of sense and movement. But the senses are inoperative without corporeal organs, as shown above. Therefore, the soul was not made without the organs of the body.

If, however, the human soul does not need the senses in order to understand, and for this reason is said to have been created apart from the body, we are compelled to say that before being united to the body, it understood by itself all scientific truths. In fact, the Platonists granted this,¹ when they held that ideas—which in Plato’s opinion are the separate intelligible forms of things—are the cause of knowledge: hence the separate soul, since there was no obstacle in the way, received full knowledge of all sciences. We must therefore say, since it is found to be ignorant when united to the body, that it forgets the knowledge it had previously. The Platonists grant this also, and allege as a proof of this that however ignorant a man may be, if he be questioned methodically about things that are taught in the sciences, he will answer the truth: thus if a man has forgotten some of the things which he knew before, and some one suggests to him consecutively the things which he has forgotten, he recalls them to his memory. Hence it also followed that to learn is nothing else than to remember. Accordingly, it follows as a necessary consequence of this opinion that union with the body hinders the soul from understanding. Now nature does not unite a thing to that which causes an obstacle to its operation; rather, it unites it to that by which its operation is rendered more prompt. Consequently, the union of body and soul will not be natural, and so man will not be a natural thing, nor will his generation be natural. These statements are clearly false.

Again. If a man who is ignorant of the sciences be questioned about matters pertaining to the sciences, he will not answer the truth except as regards universal principles of which no one is ignorant, since they are known to all in the same way and naturally. Afterwards however, if he be questioned consecutively, he will answer the truth about things closely connected with the principles, while bearing those principles in mind; he will continue to do so as long as he is able to apply the force of those principles to the matters on which he is questioned. From this, accordingly, it is clear that knowledge is caused anew in the person questioned by the first principles, and not by the remembrance of a knowledge he had possessed before.

Again. As nature is always directed to one thing, of one power there must be naturally one object (for instance, color is the object of sight, sound of hearing). Therefore, the intellect, since it is one power, has one natural object, of which it has knowledge essentially and naturally. And this object must be that under which are comprised all things known by the intellect, just as under “color” are comprised all colors, which are essentially visible. Now this is no other than being. Therefore, our intellect knows being naturally, and whatever is essentially comprised under being as such; on this knowledge is based the knowledge of first principles, such as “nothing is at once affirmed and denied,” and the like. Consequently, these principles alone are known naturally by our intellect, while conclusions are known through them, even as through color the sight knows both common and accidental sensibles.

Again. If all souls existed before the bodies to which they are united, it would seem to follow that the same soul is united to different bodies according to the vicissitudes of time. In fact, this is an evident consequence of the opinion of those who hold the eternity of the world. For, if men have been begotten from eternity, it follows that an infinite number of human bodies have been begotten and corrupted during the whole course of time. Therefore, we must say either that an actually infinite number of souls preexisted, if each soul is united to a single body, or—if the number of souls be finite—that the same soul is united at one time to this, at another time to that body. And the same would seem to follow if we suppose that souls existed before bodies, but that generation was not from eternity. For although it be supposed that the begetting of men has not always been, one cannot doubt that it can be of infinite duration, because each man is so formed by nature that, unless he be accidentally hindered, he is able to beget another even as he himself was begotten of another. Yet this is impossible if, supposing a finite number of souls, one soul cannot be united to several bodies. Therefore, several who have asserted the existence of souls before bodies maintained the transmigration of souls. But this is impossible. Therefore, souls did not exist before bodies.

That one soul cannot possibly be united to different bodies is proved thus. Human souls do not differ specifically from one another, but only numerically, or else men would also differ in species from one another. Now numerical distinction arises from material principles. Consequently, the distinction among human souls will have to be taken from something material. Not, however, as though matter were part of the soul: for it has been shown above¹ that the soul is an intellectual substance and that no such substance has any matter. It remains, therefore, that in the manner indicated above,² the distinction and plurality of souls must be taken from their relation to the different matters to which souls are united. Consequently, if there are different bodies, they must have different souls united to them. Therefore, one is not united to several.

Again. It has been proved above¹ that the soul is united to the body as its form. Now forms must be proportionate to their respective matters, since they are related the one to the other as potency to act: for the proper act corresponds to the proper potency. Therefore, one soul is not united to several bodies.

Moreover. The power of the mover should be proportionate to its mobile: for not every power moves every movable. Now it cannot be said that the soul, even were it not the form of the body, is not its mover, for the animate differs from the inanimate by sense and movement. Therefore, different souls must correspond to different bodies.

Again. In things subject to generation and corruption, the same identical thing cannot be reproduced by generation: for, since generation and corruption are movements towards substance, in things that are generated and corrupted the substance does not remain the same, as it does in things that are moved locally. Now, if the one soul is united successively to various generated bodies, the same identical man will be reproduced by generation. This is a necessary consequence for Plato, who said that man is a soul clad with a body.¹ It also follows for all the others, because, since the unity (like the being) of a thing follows its form, it follows that those things are one in number whose form is one in number. Therefore, it is not possible for one soul to be united to several bodies: and from this it follows also that neither were souls before bodies.

The Catholic faith declares itself in agreement with this truth. For it is said in the Psalm: he who fashions the hearts of them all (Ps 33[32]:15), namely, because God fashioned a soul for each one separately, and neither created them all together, nor united one to different bodies. Hence it is also declared in the book De ecclesiasticis dogmatibus, 14: we affirm that the souls of men were not created from the beginning together with other intellectual natures, nor all at the same time, as Origen pretended.

The arguments by which it is proved that souls have existed from eternity, or that they at least existed before bodies,¹ are easily solved.

For the first statement, that the soul has the power to be always, must be granted, but it must be observed that the power and potency of a thing extend not to what has been, but to what is or will be: therefore, possibility has no place in the past. Therefore, from the fact that the soul has the power to be always we may conclude not that it always was, but that it always will be.

As to the second objection about the eternity of the truth which the soul understands, we must observe that the eternity of a truth understood may be taken in two ways: in one way, as to the thing understood; in another as to that whereby it is understood. If the understood truth be eternal as regards the thing understood, it follows that the thing understood is eternal, but not the one who understands. But if the understood truth be eternal as to that whereby it is understood, it would follow that the soul which understands it is eternal. Now the understood truth is eternal not in the latter but in the former way, for it is clear from what has been said that the intelligible species, by which our soul understands truth, are acquired by us from the phantasms through the active intellect.¹ Hence it cannot be inferred that the soul is eternal, but that the truths understood are based on something eternal, for their foundation is in the first truth, as in the universal cause which contains all truth. But the soul is compared to this eternal thing not as subject to form, but as a thing to its proper end, because the true is the good of the intellect and its end.² Now from a thing’s end we can argue about its duration, just as we can argue about its beginning from its efficient cause, since what is directed to an eternal end must be capable of enduring forever. Consequently, from the eternity of intelligible truth we can prove that the soul is immortal, but not that it is eternal. That neither can the latter be proved from the eternity of the agent is clear from what has been said above³ when we were discussing the eternity of creatures.

The third objection which refers to the perfection of the universe is not cogent. For the perfection of the universe regards the species, not the individuals, since the universe is continually receiving an addition of individuals to the preexisting species. Now human souls do not differ specifically among themselves, but only numerically, as we have proved.¹ Consequently, it is not inconsistent with the perfection of the universe if new souls be created.

Hence we may gather the reply to the fourth objection. For it is stated at the same time that God finished his work and that he rested . . . from all his work which he had done (Gen 2:2). Since, then, the ending or perfecting of creatures regards the species and not the individuals, so God’s rest must be understood to refer to the cessation from forming new species, but not new individuals, the like of which have existed before in the species. Accordingly, as all human souls are of one species, even as are all men, it is not incompatible with the aforesaid rest if God creates new souls from day to day.

It must, however, be observed that we do not find it stated by Aristotle that the human intellect is eternal; yet he is accustomed to say this of those things which, in his opinion, always have been. But he declares that it is everlasting,¹ and this can be said of those things that always will be, although they have not always been. Hence in excluding the intellective soul from the conditions of other forms, he did not say that this form was before matter—and yet Plato said this of ideas, so that it would seem consistent with the subject of which he (Aristotle) was treating that he should say something of the kind of the soul—but he said that it remains after the body.²

That the soul is not made of God’s substance

From the foregoing it is clear that the soul is not of God’s substance.

For it has been shown above¹ that the divine substance is eternal, and that nothing pertaining to it begins anew. But human souls did not exist before bodies, as we have proved.² Therefore, the soul cannot be of the divine substance.

Moreover. It was shown above¹ that God cannot be the form of anything. But the soul is the form of the body, as we have proved.² Therefore, it is not of the divine substance.

Again. That from which something is made is changed in some way. But God is utterly unchangeable, as we proved above.¹ Therefore, it is impossible for anything to be made from him.

Moreover. The soul shows evident signs of variation in knowledge and virtue, and their opposites, but in God there is no variation whatever, neither essential nor accidental.¹

Again. It was shown above¹ that God is pure act in which there is no potency, but in the human soul we find both potency and act, for besides the active intellect, it contains the possible intellect which is in potency to all that is intelligible, as shown above.² Therefore, the human soul is not from the divine nature.

Again. Since the divine substance is altogether indivisible,¹ the soul cannot be a part of it, but only the whole. Now the divine substance cannot possibly be but one, as we showed above.² It follows, therefore, that there would be for all men only one soul as regards the intellect: and this has been refuted above.³ Therefore, the soul is not from the divine substance.

This opinion arose apparently from a triple source.

For some maintained that no substance is incorporeal. Consequently, they asserted that God is the most noble body (whether this be air, fire, or any other thing that they considered to be a principle) and they affirmed that the soul was of the nature of this body. For they all ascribed to the soul whatever they considered to be a principle, as Aristotle says in On the Soul 1:¹ and thus it followed that the soul is from the divine substance. From this root sprang the opinion of Manes, who thought that God is a bright body extending through infinite space, of which he said the human soul is a fragment.²

But this opinion was refuted above, both because we proved that God is not a body¹ and because we have shown that neither the human soul nor any intellectual substance is a body.

Some have maintained that for all men there is but one intellect, whether active only, or both active and possible, as stated above.¹ And since the ancients asserted that every separate substance is God, it followed that our soul (that is, the intellect by which we understand) is of the divine nature. Hence even nowadays certain adherents to the Christian faith, who hold that the active intellect is a separate being, say expressly that the active intellect is God.

But this opinion about the unity of our active intellect was disproved above.¹

Possibly, this opinion may also have arisen from the very likeness of our soul to God. For it is on account of man’s soul that intelligence, which is esteemed most proper to God, is found to be befitting to no substance in this lower world, save man alone. Hence it might seem that the soul was allied to the divine nature: and especially so to those men who were convinced of the human soul’s immortality.

Moreover, this would seem to be confirmed by the fact that after it had been said: let us make man to our image, after our likeness (Gen 1:26), it is added: God formed man of dust from the ground, and breathed into his nostrils the breath of life (Gen 2:7). From which text some wished to conclude that the soul is of the divine nature, since he who breathes into another’s face puts forth into another the identical thing which was in himself. And so Scripture would seem to imply that God put into man something divine in order to give him life.

But the aforesaid likeness does not prove that man is a part of the divine substance: for in understanding he suffers from manifold defects, which cannot be said of God. Hence this likeness indicates an imperfect image rather than consubstantiality. In fact Scripture indicates this when it says that man was made to God’s image. Hence the aforesaid breathing shows that life came forth from God into man by way of a certain likeness, and not according to identity of substance. For which reason also the spirit of life is stated to have been breathed into his face, because, since the organs of several senses are situated in this part of the body, the signs of life are more evidenced in the face. Accordingly, God is said to have breathed the spirit into man’s face, because he gave man the spirit of life, but not by parting it from his own substance. For he who breathes the breath of his body into the face of someone, from which the metaphor is apparently taken, blows into his face the air, but does not send forth part of his substance into him.

That the human soul is not transmitted with the semen

It may be shown from the foregoing that the human soul is not transmitted with the semen, as though it were sown by coition.

For any principles whatsoever that cannot exercise their operations without the body cannot begin to exist apart from the body, because a thing’s being is proportionate to its operation (since everything operates according as it is a being). On the other hand, those principles which exercise their operations without the body are generated apart from the generation of the body. Now the operation of the nutritive and sensitive soul cannot be without the body, as is evident from what has been said,¹ whereas the operation of the intellective soul is not exercised through an organ of the body, as stated above.² Consequently, the nutritive and sensitive souls, but not the intellective soul, are generated through the generation of the body. Now the transmission of the semen is directed to the generation of the body. Therefore, the nutritive and sensitive souls, but not the intellective soul, begin to exist through the transmission of the semen.

Again. If the human soul began to exist by transmission with the semen, this could only be in two ways. In one way, so that we understand it to be in the semen actually, as though it were accidentally severed from the soul of the generator, just as the semen is severed from the body. This may be seen in annulose animals that live after being cut in two, and in which there is one soul actually and several in potency: for when the body of such an animal is divided, the soul begins to be actually in each living part. In another way, so that we understand the semen to possess a virtue productive of the intellective soul: and thus the intellective soul would be in the semen virtually, but not actually.

But the former of these is impossible for two reasons. First because, since the intellective soul is the most perfect of souls and endowed with the highest power, its proper matter is a body having a great variety of organs by which its manifold operations can be accomplished. Consequently, it cannot possibly be actually in the separated semen, since not even the souls of perfect irrational animals are multiplied by division, as happens in annulose animals. Second because, since the intellect (which is the proper and principal power of the intellective soul) is not the act of any part of the body, it cannot be accidentally divided through the body being divided: consequently, neither can the intellective soul.

The second is also impossible. For the active force in the semen promotes the generation of the animal by transmuting the body, for a material force cannot act otherwise. Now every form that begins to exist through the transmutation of matter has a being dependent on matter, because the transmutation of matter reduces it from potency to act, and thus terminates in the actual being of matter, which results from its union with a form. Hence if by this the being of the form also begins simply, the being of the form will consist merely in its being united to matter, and consequently the form will be dependent on matter for its being. Therefore, if the human soul is brought into being by an active force in the semen, it follows that its being is dependent on matter, like the being of other material forms. But the contrary of this has been proved above.¹ Therefore, the intellective soul is in no way brought into being through the transmission of the semen.

Moreover. Every form that is brought into being through the transmutation of matter is brought forth from the potency of matter, since the transmutation of matter is its reduction from potency to act. Now the intellective soul cannot be brought forth from the potency of matter: for it has been shown above¹ that the intellective soul surpasses the whole potency of matter, since it has an operation apart from matter, as was proved above.² Therefore, the intellective soul is not brought forth into being through the transmutation of matter; and consequently neither by the action of a power residing in the semen.

By this is excluded the error of Apollinaris and his followers, who said that souls are generated by souls, as bodies by bodies.¹

That the human soul is brought into being through creation by God

From what has been said, it can be proved that God alone brings the human soul into being.

For whatever is brought into being is either generated essentially or accidentally, or is created. Now the human soul is not generated essentially, since it is not composed of matter and form, as shown above.¹ Neither is it generated accidentally: for, since it is the form of the body, it would be generated through the body being generated, which results from the active force in the semen, and this has been disproved (ch. 86. Since, then, the human soul has a beginning of its existence, for it is neither eternal nor exists before the body, as we have shown,² it follows that it comes forth into being by creation. Now we have proved that God alone can create. Therefore, he alone brings forth the human soul into being.

Moreover. Everything whose substance is not its being has an author of its being, as shown above.¹ Now the human soul is not its own being: for this is peculiar to God alone, as already proved.² Therefore, it has an active cause of its being. But that which has being of itself is also caused by itself. In contrast, that which does not have being of itself, but only together with some other thing, is caused not by itself, but through this other thing being caused; thus the form of fire is caused when the fire is made. Now it is proper to the human soul, as compared with other forms, to be subsistent in its own being, and to communicate to the body the being proper to itself.³ Therefore, the human soul has its becoming of itself, in contrast to other forms which have their becoming accidentally, through the making of the composite. But, since the human soul does not have matter as its part, it cannot be made from something. It remains, therefore, that it is made from nothing: and thus it is created. And seeing that creation is the proper work of God, as we proved above,⁴ it follows that it is created immediately by God alone.

Further. Things belonging to the same genus come into being in the same way, as we proved above.¹ Now the soul belongs to the genus of intellectual substances: and it is inconceivable that these should come into being save by the way of creation. Therefore, the human soul comes into being through creation by God.

Again. Whatsoever is brought into being by an agent acquires from the latter either something that is the principle of being in that particular species, or absolute being itself. Now the soul cannot be brought into being in such a way as to acquire something as the principle of its being. (This is what happens in things composed of matter and form, which are generated through acquiring a form in act.) For the soul does not contain something in itself by way of principle of its being, for it is a simple substance, as was shown above.¹ Hence it remains that it is not brought into being by an agent except by receiving from it being absolutely. Now being is the proper effect of the first and universal agent: for secondary agents act by impressing the likeness of their forms on the things they make, which likenesses are the forms of the things made. Therefore, the soul cannot be brought into being except by the first and universal agent, which is God.

We also find this implied in Sacred Scripture. For whereas while speaking of the formation of other animals, it ascribes their souls to other causes—for instance, when it says: let the waters bring forth swarms of living creatures (Gen 1:20), and in like manner as to other things—when it comes to man, it indicates the creation of the soul by God, by saying: God formed man of dust from the ground, and breathed into his nostrils the breath of life (Gen 2:7).

By this is excluded the error of those who hold that souls were created by angels.

Arguments for proving that the human soul is formed from the semen

Nevertheless, there are some objections to the foregoing.¹

For, since man is an animal inasmuch as he has a sensitive soul, and the notion of “animal” applies univocally to man and other animals, it would seem that man’s sensitive soul is of the same genus as the souls of other animals. Now things of the same genus have the same manner of coming into being. Therefore, the sensitive soul of man, as also of other animals, comes into being through a force residing in the semen. But the intellective and sensitive soul are the same in man, as we proved above.¹ Consequently, it would seem that the intellective soul also comes into being through a seminal power.

Again. Since the soul is the form of the body, it is united to the body in being. Now, things that are one in being are the term of one action and of one agent: for if there were several agents, and consequently several actions, effects diverse in being would result. Consequently, the being of soul and body must be the term of the one action of one agent. But it is clear that the body results from the action of a power in the semen. Therefore, the soul, which is its form, is the effect of the same action, and not of some separate agent.

Moreover. Man generates his like in species by a power residing in the semen after separation. Now, every univocal agent generates its like in species through causing the form of the thing generated, which derives its species from that form. Therefore, the human soul, from which man derives his species, is produced by a power residing in the semen.

Again. Apollinaris argues as follows.¹ Whoever completes a work cooperates with the agent. But if souls are created by God, he completes the generation of children, who are sometimes born of adulterers. Therefore, God cooperates with adulterers, and this seems inadmissible.

Again, in a book¹ ascribed to Gregory of Nyssa, we find arguments in support of the same statement. This is how he argues. Soul and body together make one thing, and this is one man. If, therefore, the soul is made before the body, or the body before the soul, one and the same thing will precede and follow itself, which is seemingly impossible. Therefore, body and soul are made at the same time. But the body begins to exist at the separation of the semen. Therefore, the soul also is brought into being through the separation of the semen.

Again. The operation of an agent would seem to be imperfect if he does not bring an entire thing into being, but only some part of it.¹ Therefore, if God were to bring the soul into being,while the body was formed by the power of the semen, which two things are parts of one man, the operation of both God and the seminal power would seem to be imperfect, which is clearly inadmissible. Hence man’s soul and body are produced by one and the same cause. Now, it is clear that man’s body is produced by the power of the semen. Therefore, the soul is also.

Again. In everything generated from seed, all the parts of the thing generated are together virtually contained in the seed, though they do not appear actually: Thus in wheat or any other seed we see that the grass with stem, stalks, fruit, and beard are virtually contained in the original seed; afterwards the seed spreads forth and by a kind of natural consequence reaches perfection without taking to itself anything outside itself.¹ Now it is clear that the soul is part of man. Therefore, the human seed contains virtually the human soul, and this does not take its origin from any external principle.

Moreover. Things that have the same process and term must have the same principle of origin. Now in the generation of a man, we find the same process and term in the body as in the soul. For the soul’s operations become more and more manifest as the members are developed in shape and size: thus the operation of the nutritive soul is apparent at first; afterwards, the operation of the sensitive soul; lastly, the body being fully developed, the operation of the intellective soul.¹ Therefore, the body and soul have the same principle. But the principle of origin in the body is through the separation of the semen. Therefore, the same is the principle of the soul’s origin.

Again. That which is conformed to a thing is fashioned by the action of the thing to which it is conformed: for instance, the wax that is conformed to the seal receives this conformity from the impression of the seal. Now it is evident that the body of a man or of any animal is conformed to its own soul, because its organs are so arranged as the soul’s operations require for their exercise.¹ Therefore, the body is formed by the action of the soul: therefore, Aristotle says that the soul is the efficient cause of the body.² But this would not be so were not the soul in the semen, because the body is fashioned by the power that is in the semen. Therefore, the human soul is in the semen, and consequently takes its origin from the separation of the semen.

Again. Nothing lives except by a soul. Now the semen is living.¹ This is proved in three ways. First, because it is severed from a living being. Second, because the semen gives signs of vital heat and vital operations, which are indications of a living thing. Third, because the seeds of plants, unless they had life in themselves, when put into the soil could not gather heat from the soil, which is inanimate, so as to live. Therefore, the soul is in the semen, and consequently it originates with the severing of the semen.

Moreover. If the soul were not before the body, as we have proved,¹ and did not begin to be at the severance of the semen, it follows that the body is formed first, and the newly created soul infused into the body afterwards. Now, were this true, it would further follow that the soul is for the sake of the body, because that which is on another’s account is found to come after it, as clothes are made on account of man. But this is false, since the body is more for the soul’s sake, since the end is always of greater excellence. We must, therefore, conclude that the soul originates together with the severance of the semen.

For the easier solution of the foregoing arguments, we must first of all set down certain points in order to explain the order and process of the generation of man, as well as of animals in general.

In the first place, then, it must be observed that the opinion of those is false who say that the vital operations that appear in the embryo before its ultimate completion, do not proceed from a soul or soul’s power, existing therein, but from the soul of the mother. For if this were true, the embryo will no longer be an animal, since every animal consists of soul and body. Moreover, vital operations do not proceed from an extrinsic active principle, but from an internal force; it is in this that inanimate things differ from the living, to which it properly belongs to move themselves. That which is nourished assimilates nourishment: therefore, in the subject nourished there must be an active nutritive power, since the agent produces its like. And much more evident is this in the operation of the senses: because to see and to hear are competent to a person through some faculty existing in him and not in another. Therefore, if the embryo is observed to be nourished and even to sense before its final development, that cannot be ascribed to the soul of the mother.

And yet it cannot be said that the soul is in the semen from the very beginning as to its complete essence, and that the operations of the soul are not apparent on account of the lack of organs. For, since the soul is united to the body as its form, it is not united to a body other than one of which it is properly the act. Now the soul is the act of an organic body.¹ Consequently, the soul is not actually in the semen before the organization of the body, but only potentially or virtually. And thus Aristotle says that seed and fruit are potentially living as long as they put aside, i.e., are without, the soul; yet the thing of which the soul is the act is potentially living, but is not without a soul.²

It would also follow, if the soul were in the semen from the beginning, that the generation of an animal would be by mere severance, as happens in annulose animals, where two are made from one. For if the semen were animated as soon as severed, it would at once have a substantial form. Now every substantial generation precedes, and does not follow, the substantial form; if any changes follow the substantial form, they are directed not to the being, but to the well-being of the thing generated. Accordingly, the generation of the animal would be completed in the mere severance of the semen: and all subsequent changes would have nothing to do with generation.

Even more absurd would this be if applied to the rational soul: both because it cannot possibly be divided according to the division of the body, so that it be possible for it to be in the semen after severance, and because it would follow that whenever pollution occurs without conception taking place, rational souls would nevertheless be multiplied.

Nor can it be asserted, as some say, that although from the moment of severance the soul is not in the semen actually but virtually, on account of the lack of organs, yet this very power of the semen (which is a body capable of receiving organs though it has them not actually) is proportionately a potential but not an actual soul to the semen. And since the life of a plant requires fewer organs than the life of an animal, this same power of the semen becomes a vegetative soul when the semen is first sufficiently prepared for vegetative life. Then, when the organs have been yet more perfected and multiplied, the same power advances to the state of a sensitive soul. Further still, the form of the organs being perfected, the same soul becomes rational—not indeed by the action of this seminal power, but by the action of an external agent, for which reason they imagine Aristotle to have said that the intellect is from without.¹ For, according to this opinion, it would follow that the same identical power is at one time a purely vegetative soul, and afterwards a sensitive soul, so that the substantial form itself would be perfected more and more by stages. It would also follow that the substantial form would be brought from potency to act not at once, but by degrees. And again, that generation, like alteration, is a continuous movement. All of which things are impossible in nature.

A conclusion still more inadmissible would follow, namely, that the rational soul is mortal. For nothing that accrues as a form to that which is corruptible makes it naturally incorruptible, or else a corruptible thing would be changed into an incorruptible one, which is impossible, since they differ in genus, as stated in 10 Metaphysics.¹ Now, since in the aforesaid process the substance of the sensitive soul is stated to be generated accidentally by the generated body, it must be corruptible at the corruption of the body. If, therefore, the same soul becomes rational by a light introduced within it, which light is related to it as a form (for the sensitive is potentially intellective), it necessarily follows that the rational soul perishes when the body perishes. And this is impossible as we proved above,² and as the Catholic faith teaches.

Therefore, the selfsame power which is severed together with the semen and is called the formative power is not the soul, nor does it become the soul in the process of generation: but, since it is based, as on its proper subject, on the (vital) spirit contained in the frothy semen, it causes the formation of the body insofar as it operates by power of the father’s soul, to whom generation is ascribed as the principal agent, and not by power of the soul of the person conceived, even after the soul is in that person: for the subject conceived does not generate itself, but is generated by the father.

This is clear to anyone who considers each power of the soul separately. For it cannot be ascribed to the soul of the embryo by reason of the generative power, not only because the generative power does not exercise its operation until the work of the nutritive and augmentative powers, which are its auxiliaries, is completed (since to generate belongs to that which is perfect), but also because the work of the generative power is directed not to the perfection of the individual, but to the preservation of the species.

Nor again can it be ascribed to the nutritive power, whose work is to assimilate nourishment to the subject nourished, which is not apparent here, for in the process of formation the nourishment is not assimilated to something already existing, but is advanced to a more perfect form and more approaching to a likeness to the father. Likewise, neither can it be ascribed to the augmentative power, for it belongs to this power to cause a change not of form, but of quantity. As to the sensitive and intellective part, it is clear that it has no operation appropriate to such a formation.

It remains, then, that the formation of the body, especially as regards the foremost and principal parts, is not from the form of the subject generated, nor from a formative power acting by power of that form, but from (a formative power) acting by power of the father’s generative soul, whose work is to produce the specific like of the generator.

Accordingly, this formative power remains the same in the aforesaid spirit from the beginning of the formation until the end. Yet the species of the subject formed does not remain the same, because at first it has the form of semen, afterwards of blood, and so onwards until it arrives at its final complement. For although the generation of simple bodies does not proceed in order (since each of them has an immediate form of prime matter), in the generation of other bodies there must be an order in the generations because of the many intermediate forms between the first elemental form and the final form which is the term of generation. And therefore there are a number of generations and corruptions following one another.

Nor is it unreasonable if one of the intermediates be generated and then at once interrupted, because the intermediate stages do not have a complete species but are on the way to a species: hence they are generated not so that they may remain, but that the final term of generation may be reached through them. Nor need we wonder if the transmutation of generation is not continuous throughout, and that there are many intermediate generations, for this also happens in alteration and growth, since neither alteration nor growth is continuous throughout, but only local movement is truly continuous, as we find proved in Physics 8.¹

Accordingly, the more noble a form is and the further removed it is from the elemental form, the more numerous must be the intermediate forms through which the ultimate form is reached by degrees, and consequently the more numerous will be the intermediate generations. Therefore, in the generation of an animal or a man in which the form is most perfect, there are many intermediate forms and generations, and consequently corruptions, since the generation of one is the corruption of another.¹ Therefore, the vegetative soul, which comes first when the embryo lives the life of a plant, is corrupted, and is succeeded by a more perfect soul which is both nutritive and sensitive, and then the embryo lives an animal life. When this is corrupted, it is succeeded by the rational soul introduced from without, although the preceding souls were produced by the power in the semen.

These being seen, it is easy to answer the objections.¹

For in reply to the first objection, where it is stated that the sensitive soul must have the same manner of origin in man and in irrational animals, because “animal” is predicated of both univocally, we say that this is not necessary. For although the sensitive souls in man and dumb animals agree generically, they differ specifically, like the things of which they are the forms. For just as the animal that is a man differs specifically from other animals in the point of being rational, so the sensitive soul of man differs specifically from the sensitive soul of a dumb animal in this: it is also intellective. Therefore, the sensitive soul in the dumb animal has no more than the sensitive faculty: and consequently neither its being nor its operation is raised above the body. And so it must be generated together with the body, and perish when the body perishes. On the other hand, the sensitive soul in a man, through having an intellective power in addition to the sensitive nature (from which it follows that it is raised above the body both in being and in operation), is neither generated through the generation of the body, nor perishes through the body’s corruption. Hence the different manner of origin in the aforesaid souls is not on the part of the sensitive faculty from which the generic nature is taken, but on the part of the intellective faculty, from which the specific difference is derived. Therefore, we can conclude a difference not of genus but only of species.

When it is objected in the second place that the thing conceived is an animal before a man, this does not prove that the rational soul is transmitted together with the semen. For the sensitive soul by which it was an animal does not remain, but is succeeded by a soul that is both sensitive and intellective, by which it is both animal and man at the same time, as explained above.

The statement in the third objection—that the actions of different agents do not terminate in one thing made—must be understood as referring to different agents of which one is not ordered to the other. For if they be ordered the one to the other, they must have one effect, for the first active cause acts on the effect of the secondary active cause more intimately than does the secondary cause. Hence we find that an effect produced by a principal agent through an instrument is more properly ascribed to the principal agent than to the instrument. Now it happens sometimes that the action of the principal agent attains to something in the effect produced, to which the action of the instrument does not attain: thus the vegetative power produces the species of flesh, which the heat of fire that is its instrument cannot produce, although it acts dispositively to it by dissolving and consuming. Since, then, every active force of nature is compared to God as an instrument is compared to the first and principal agent, nothing hinders the action of nature from terminating in a part of man and not in the whole (which is the effect of God’s action) in one and the same subject generated which is a man. Accordingly, the human body is fashioned at the same time both by the power of God as the principal and first agent, and by the power of the semen as secondary agent, but God’s action produces the human soul, which the seminal power cannot produce, but to which it disposes.

Hence the reply to the fourth objection is clear. For thus a man begets his like in species insofar as the seminal power in him operates dispositively towards the ultimate form from which man derives his species.

That God should cooperate with adulterers in the action of nature involves no contradiction. For it is not the nature but the will that is evil in adulterers: the action which proceeds from their seminal virtue is natural and not voluntary. Therefore, it is not unreasonable that God cooperate in their action by giving it its ultimate perfection.

As to the sixth objection, it is clear that the conclusion does not necessarily follow. For even if we grant that man’s body is fashioned before the soul is created, or vice versa, it does not follow that the selfsame man precedes himself, since a man is not his body nor his soul. But it follows that some part of him precedes the other. In this there is nothing unreasonable, because matter precedes form in point of time. (I say “matter” considered as being in potency to form, but not as actually perfected by a form, for it is thus simultaneous with the form.) Accordingly, the human body precedes the soul in point of time, considered as in potency to the soul and as not yet having a soul, but then it is human not actually, but only potentially. On the other hand, when it is human actually as being perfected by the human soul, it neither precedes nor follows the soul, but is simultaneous with it.

Nor again does it follow that the operation both of God and of nature is imperfect if the soul is not produced by the seminal virtue, but only the body, as the seventh argument inferred. For both body and soul are made by the power of God, although the fashioning of the body is from him by means of the natural power in the semen, while he produces the soul immediately. Neither does it follow that the action of the seminal power is imperfect, since it fulfils the purpose for which it is intended.

It must also be noted that the semen contains virtually whatever does not surpass a corporeal power (for instance, the grass with the stem, stalks, and so forth). Hence we cannot conclude that the part of man which surpasses the whole corporeal power is contained virtually in the semen, as the eighth argument inferred.

That the operations of the soul seem to develop in the process of human generation (according as the parts of the body develop) does not prove that the human soul and body have the same principle, as the ninth argument suggested, but it proves that the disposition of the body’s parts is necessary for the soul’s operation.

The statement of the tenth objection—that the body is conformed to the soul, and that for this reason the soul fashions a body like to itself—is partly true and partly false. For if it be understood of the soul of the begetter, the statement is true, but it is false if it be referred to the soul of the begotten. For the body is not formed by the power of the soul of the begotten, as regards the body’s foremost and principal parts, but by the power of the soul of the begetter, as we proved above.¹ For all matter is similarly configured to its form, and yet this configuration results not from the action of the subject generated, but from the action of the generator.

As to the eleventh objection about the life of the semen at the beginning of its severance, it is clear from what has been said that it is not living except potentially. Therefore, it has a soul then not actually, but virtually. In the process of generation, it has a vegetative and a sensitive soul by the virtue of the semen, which do not remain but pass away when the rational soul takes their place.

Nor again does it follow that the soul is for the sake of the body if the fashioning of the body precedes the human soul, as the twelfth objection inferred. For one thing is for another’s sake in two ways. First, for the sake of its operation, or preservation, or any like thing consequent upon being, and such things are posterior to the thing for the sake of which they are: thus clothes are for man, and tools for the workman. Second, a thing is for another’s sake (that is, for the sake of its being): thus a thing which is for the sake of another precedes the latter in the order of time, but follows it in the order of nature. It is in this way that the body is for the sake of the soul, just as all matter is for the sake of a form. It would be otherwise if from soul and body there resulted a thing that is not one in being, as those assert who deny that the soul is the form of the body.

That an intellectual substance is united as a form to no other than the human body

Since it has been proved¹ that a certain intellectual substance (namely, the human soul) is united to a body as its form, it remains for us to ask whether any intellectual substance can be united as form to any other body. Indeed, as regards heavenly bodies, we have shown above² what was Aristotle’s opinion as to their being animated with an intellective soul, and that Augustine leaves the question unsolved. Therefore, the present inquiry must be confined to elemental bodies.

That an intellectual substance is not united as form to any elemental body save that of man is evidently clear. For were it united to some other, it would be united either to a mixed or to a simple body. But it cannot be united to a mixed body, because that body, in respect of its genus, would have to surpass other mixed bodies in evenness of temperament, since we see that mixed bodies have forms so much the more noble the nearer they approach to an even temperament. Thus, if that which has a most noble form (such as an intellectual substance) be a mixed body, it must have a most even temperament. For this reason we find that a soft flesh and a delicate touch are signs of a keen understanding.¹ Now the most even temperament is that of the human body. Consequently, if an intellectual substance be united to a mixed body, the latter must have the same nature as the human body. Moreover, its form would be of the same nature as the human soul if it were an intellectual substance. Therefore, there would be no specific difference between that animal and man.

Again, neither can an intellectual substance be united as form to a simple body, such as air, water, fire, or earth. For each of these bodies is similar in the whole and in the parts, since a part of air has the same nature and species as the whole air, for it has the same movement, and the same applies to the others. Now like movers have like forms. Accordingly, if any part of any one of the aforesaid bodies (air, for instance) be animated with an intellectual soul, for the same reason the whole air and all its parts will be animated. But this is seen clearly to be false, because there is no sign of vital operations in the parts of the air or of other simple bodies. Therefore, an intellectual substance is not united as form to any part of the air or of similar bodies.

Again. If an intellectual substance be united as form to one of the simple bodies, it will have either an intellect only, or it will have other powers (for instance, those which belong to the sensitive or to the nutritive part, as in man). If it have the intellect only, there is no use in its being united to the body. For every form of a body exercises a proper operation through the body. And the intellect has no operation pertaining to the body, except insofar as it moves the body: because understanding is not an operation that can be exercised by an organ of the body; nor is willing, for the same reason. Again, the movements of the elements are from natural movers—namely, their generators—and they do not move themselves. Therefore, it does not follow that they are animated because they have movement. If, on the other hand, the intellectual substance, which is supposed to be united to an element or to a part of one, have other parts of the soul, since these parts are parts of certain organs, it follows that we shall find diversity of organs in the body of the element. But this is inconsistent with its simplicity. Therefore, an intellectual substance cannot be united as form to an element or to a part of one.

Moreover. The nearer a body is to prime matter, the less noble it is, according as it is more in potency and less in complete act. Now the elements are nearer than mixed bodies to prime matter, since they are the proximate matter of mixed bodies. Consequently, the elemental bodies are less noble than mixed bodies as to their species. Therefore, since the more noble bodies have more noble forms, it is impossible that the noblest form of all, which is the intellective soul, be united to the bodies of the elements.

Again. If the elemental bodies or any parts of them were animated by the noblest kind of soul, which is the intellective soul, it would follow that the more akin a body is to the elements, the nearer it approaches to life. Now this does not appear to be the case, but rather the contrary: for plants have less of life than animals, and yet they are more akin to earth; while minerals, which are still more akin, have no life at all. Therefore, an intellectual substance is not united as form to an element or to a part of one.

Further. Exceeding contrariety is destructive of life in all corruptible movers: for excessive heat or cold, wet or dryness, are fatal to animals and plants. Now these contraries exceed especially in the elemental bodies. Therefore, life cannot possibly be in them. Therefore, it is impossible for an intellectual substance to be united to them as their form.

Moreover. Although the elements are incorruptible as a whole, each of their parts is corruptible as having contrariety. If, therefore, some parts of the elements have cognitive substances united to them, it seems that the power of discerning corruptives should especially be ascribed to them. Now this is the sense of touch, which discriminates between hot and cold and like contraries: and for this very reason it is in all animals, as though it were necessary for preservation from corruption. But this sense cannot possibly be in a simple body, since the organ of touch needs to have contraries not actually but potentially, and this is the case only in mixed and tempered bodies. Therefore, it is not possible that any parts of the elements be animated with an intellective soul.

Again. Every living body has some kind of local movement proceeding from its soul: for the heavenly bodies (if indeed they be animated)¹ have a circular movement; perfect animals a progressive movement; oysters a movement of expansion and contraction; plants a movement of increase and decrease—all of which are kinds of local movement. Whereas in the elements there is no sign of movement proceeding from a soul, but only such as is natural. Therefore, they are not living bodies.

If, however, it be said that although an intellectual substance be not united as a form to an elemental body or part thereof, yet it is united to it as its mover, the first is impossible if applied to the air. For, since a part of the air has no bounds of its own, no determinate part of the air can have its own proper movement on account of which an intellectual substance be united to it.

Again. The movement of an elemental body can proceed from other principles besides an intellectual substance. Therefore, this movement is not a sufficient reason for intellectual substances to be naturally united to elemental bodies.

By this is excluded the opinion of Apuleius and certain Platonists, who asserted that the demons are animals with an aerial body, a rational mind, passive in soul, and eternal in duration, and that of certain heathens who held the elements to be animated (and thus they offered them divine worship).¹ Again, the opinion is refuted of those who said that angels and demons have bodies naturally united to them, which respectively partake of the nature of the higher or lower elements.

Separate substances

That there are some intellectual substances which are not united to bodies

It may be shown from the foregoing that there are some intellectual substances which are in no way united to bodies.

For it has been proved above¹ that when the body perishes, the substance of the intellect remains inasmuch as it is everlasting. And if the substance of the intellect which remains be one in all, as some assert,² it follows of necessity that it is, in its being, separate from the body. And thus our point is proved, namely, that some intellectual substance subsists apart from a body. If, however, many intellectual souls survive the destruction of bodies, it will be competent to some intellectual substances to subsist apart from a body: especially since it has been proved³ that souls do not pass from one body to another. Now this separation from bodies is accidentally competent to souls, since they are naturally forms of bodies. But that which is accidental must be preceded by that which is essential.⁴ Therefore, there are some intellectual substances, naturally prior to souls, to which it is essentially competent to subsist apart from a body.

Moreover. Whatever belongs to the generic nature must belong to the specific nature: whereas certain things belong to the specific nature which are not in the generic nature. Thus “rational” belongs to the essence of man, but not to the essence of animal. Now that which belongs to the specific nature and not to the generic nature does not of necessity belong to every species of the genus: for there are many species of irrational animals. And it belongs to the intellectual substance, by reason of its genus, to be essentially subsistent, since it has an essential operation, as we have shown above.¹ Now it belongs to the nature of an essentially subsistent thing not to be united to another. Therefore, it does not belong to the nature of an intellectual substance to be united to another, although it does belong to the nature of some intellectual substance (namely, the soul). Therefore, there are some intellectual substances that are not united to a body.

Again. The higher nature in its lowest degree touches the lower nature in its highest degree.¹ Now the intellectual nature is higher than the corporeal: and it touches it in respect of one of its parts, namely the intellective soul. Therefore, it follows that, just as the body that is perfected by the intellective soul is the highest in the genus of bodies, so the intellective soul that is united to a body is the lowest in the genus of intellectual substances. Therefore, there are some intellectual substances not united to bodies which, in the order of nature, are higher than the soul.

Again. If, in a genus, there be something imperfect, we find that there is something above it which in the order of nature is perfect in that genus.¹ Now forms that are in matter are imperfect acts, since they have not complete being. Therefore, there are some forms that are complete acts, subsistent in themselves, and having a complete species. But every form that subsists in itself without matter is an intellectual substance, since immunity from matter gives intellectual being, as was shown above.² Therefore, there are some intellectual substances that are not united to bodies: for every body is material.

Moreover. Substance can be without quantity, although there cannot be quantity apart from substance: because substance precedes the other genera in time, idea, and knowledge.¹ But no corporeal substance is without quantity. Therefore, there can be some things in the genus of substance that are altogether without a body. Now all possible natures are found in the order of things: otherwise the universe would be imperfect. Moreover, in everlasting things there is no difference between actual and possible being.² Therefore, there are some substances subsistent apart from a body, below the first substance, which is God (who is in no genus, as we proved above),³ and above the soul which is united to a body.

Further. If we find a thing composed of two, and one of these, which is the less perfect, be found to exist by itself, the one which is more perfect and less dependent on the other is also to be found by itself.¹ Now a certain substance is found to be composed of an intellectual substance and a body, as shown above.² And a body is found existing by itself, as evidenced in all inordinate bodies. Much more, therefore, are some intellectual substances found existing without being united to bodies.

Again. The substance of a thing should be proportionate to its operation, because operation is the act and the good of the operator’s substance. Now understanding is the proper operation of an intellectual substance. Therefore, an intellectual substance should be such as is competent to exercise the aforesaid operation. But since understanding is an operation that is not exercised by means of a corporeal organ, it does not need the body except insofar as intelligible objects are taken from sensibles. Yet this is an imperfect way of understanding, since the perfect way of understanding is to understand things that are intelligible by their nature. That only those things be understood which are not intelligible in themselves, but are rendered intelligible by the intellect, is an imperfect way of understanding. Therefore, if before every imperfect thing there must be something perfect in the same genus,¹ it follows that above human souls, which understand by receiving from phantasms, there are some intellectual substances which understand things that are intelligible in themselves, without receiving knowledge from sensibles, and for this reason are by their nature altogether separate from bodies.

This agrees with the opinion of Dionysius who says, in speaking of the angels, that they are understood to be immaterial and incorporeal.¹

By this is refuted the error of the Sadducees who said that there is no spirit (Acts 23:8); as also the assertion of the philosophers of old who said that every substance is corporeal;¹ and the opinion of Origen who said that (with the exception of the divine Trinity) no substance can subsist apart from a body; and of all those others who hold that all the angels, both good and bad, have bodies naturally united to them.²

It must here be noted that Aristotle attempts to prove that not only some intellectual substances exist apart from a body, but also that they are of the same number, neither more nor less, as the movements observed in the heaven.¹

Thus, he proves that in the heaven there are no movements that cannot be observed by us, from the fact that every movement in the heaven is on account of the movement of some star, which is perceptible to the senses, since the spheres carry the stars and the movement of the carrier is on account of the movement of the carried. Again, he proves that there are no separate substances from which some movement does not result in the heaven, For, since the heavenly movements are directed to the separate substances as their respective ends, if there were any separate substances besides those which he enumerates, there would be certain movements directed to them as an end. Otherwise, such movements would be imperfect. Therefore, he concludes from these premises that separate substances are not more numerous than the movements that are and can be observed in the heaven, and all the more so since there are not several heavenly bodies within the same species, so that there might also be several movements unknown to us.

But this argument is not cogent. For in things directed to an end, necessity depends on the end, as he himself teaches,¹ and not vice versa. Therefore, if (as he states) the heavenly movements are directed to separate substances as their respective ends, we cannot necessarily conclude the number of the aforesaid substances from the number of the movements. For it might be said that there are some separate substances of a higher nature than those which are the proximate ends of the heavenly movements, even as, if tools be on account of the men who work by means of them, this does not hinder there being other men who do not work immediately with those tools, but direct the workers. Hence Aristotle himself adduces this argument not as necessary, but as probable: for he says: Therefore, it is reasonable to reckon such to be the number of unchangeable substances and principles: for we may leave it to more capable persons to decide the point with certainty.²

It remains, then, to be shown that the intellectual substances that are separate from bodies are far more numerous than the heavenly movements.

For intellectual substances transcend all corporeal nature in their genus. Therefore, we must mark the degrees of the aforesaid substances according to their transcendency above corporeal nature. Now some intellectual substances are raised above corporeal substance in their generic nature alone, and are nevertheless united to bodies as forms, as shown above.¹ And since the being of intellectual substances, as regards its genus, is in no way dependent on a body, as we have proved,² we find a higher grade of the aforesaid substances, which, though not united to bodies as forms, are nevertheless the proper movers of certain definite bodies. In like manner, the nature of an intellectual substance does not depend on its causing movement, since to move is consequent upon their principal operation which is to understand. Hence there will be a yet higher grade of intellectual substances which are not the proper movers of certain bodies, but are raised above movers.

Moreover. Even as that which acts by its nature acts by its natural form, so that which acts by its intelligence acts by its intellectual form, as instanced in those who act by their art. Accordingly, as the natural agent is proportionate to the patient by reason of its natural form, so the intelligent agent is proportionate to the patient and to the thing made through the form of its intellect; in effect, the intellective form is such that it can be induced by the agent’s action into the matter which receives it. Hence the proper movers of the spheres—since they move by their intellect (if we wish to uphold the opinion of Aristotle on this point)¹—must have such intelligences as are in harmony with the movements of the spheres, and reproducible in natural things. But above these intelligible concepts we can apprehend some that are yet more universal: because the intellect apprehends the forms of things in a manner that is more universal than is their being in things: for which reason we find that the form of the speculative intellect is more universal than that of the practical intellect, and among the practical arts, the concept of the commanding art is more universal than that of the executive art. Now we must assign degrees to intellectual substances according to the degree of intellectual operation proper to them. Therefore, there are some intellectual substances above those which are the proper and proximate movers of certain definite spheres.

Again. It seems the order of the universe requires that whatever is more noble among things should exceed in quantity or number the less noble, since the less noble would seem to be for the sake of the more noble. Hence the more noble things, as existing for their own sake, should be as numerous as possible. Hence we find that incorruptible (namely, the heavenly) bodies so far surpass corruptible (or the elemental) bodies that the latter are inconsiderable in quantity as compared with the former. Now just as the heavenly bodies, being incorruptible, are more noble than the elements which are corruptible, so intellectual substances are more noble than all bodies, even as the immovable and the immaterial is more noble than the movable and material. Therefore, separate intellectual substances surpass in number the whole multitude of material things. Consequently, they are not confined to the number of heavenly movements.

Again. The species of material things are multiplied not through their matter but through their form. Now, forms existing apart from matter have a more complete and universal being than forms existing in matter: because forms are received into matter according to the receptivity of matter. Therefore, it seems that forms existing apart from matter (which we call separate substances) are not less in number than the species of material things.

Yet we do not therefore say that separate substances are the species of these sensible things, as the Platonists maintained.¹ For, since they could not attain to the knowledge of the aforesaid substances except from sensibles, they supposed those substances to be of the same species as these, or rather to be the species of these latter: just as a person who had not seen the sun, moon, and stars, and heard that they were incorruptible bodies, might call them by the names of these corruptible bodies, thinking them to be of the same species as these. Which would not be possible. In like manner, it is impossible that immaterial substances be of the same species as material, or that they be the species of the latter substances, because the specific nature of these sensible things requires matter, though not this matter, which is the proper principle of the individual: even as the specific nature of man requires flesh and bones, but not this flesh and these bones which are the principles of Socrates and Plato. Accordingly, we do not say that separate substances are the species of these sensibles, but that they are other species more noble than these, as much as the pure is raised above the mixture. And thus those substances must be more numerous than the species of these material things.

Further. The possibility of multiplication applies to a thing in its intelligible being rather than in its material being. For we grasp many things with our intellect which cannot have being in matter (the result being that any straight line can be produced mathematically, but not in nature). It is also possible for the rarefaction of bodies, the velocity of movements, the diversity of shapes to be multiplied indefinitely in thought, although it is impossible in fact. Now, separate substances have intelligible being by their nature; consequently, a greater multiplicity is possible in them than in material substances, taking into account their respective properties and natures. Now in everlasting things there is no distinction between actual and possible being.¹ Therefore, the multitude of separate substances surpasses that of material bodies.

Sacred Scripture bears witness to this. For it is stated: A thousand thousands served him, and ten thousand times ten thousand stood before him (Dan 7:10). And Dionysius says that the number of those substances surpasses all material multitude.¹

By this, we set aside the error of those who said that the number of the separate substances corresponds to the number of heavenly movements, or of the heavenly spheres. We also set aside the error of Rabbi Moses,¹ who said that the number ascribed by Scripture to the angels is not the number of separate substances, but of powers in this lower world (as if one were to give to the concupiscible power the name “spirit of concupiscence,” and so on).

That there are not several separate substances of one species

From what has been said concerning these substances, it may be shown that there are not several separate substances of one species.

For it has been proved above¹ that separate substances are subsistent quiddities. Now, the species of a thing is signified by its definition, for this is the sign of a thing’s quiddity.² Hence a subsistent quiddity is a subsistent species. Therefore, there cannot be several separate substances unless they be several species.

Further. Whatever things are the same in species but differ numerically have matter. For a difference resulting from form involves a specific difference, but that which results from matter causes a diversity of number.¹ Now, separate substances are utterly devoid of matter, whether as part of themselves, or by being united to matter as its form.² Therefore, they cannot possibly be several of one species.

Moreover. The purpose for which there are several individuals in one species in corruptible things is that the specific nature, which cannot be preserved forever in one individual, may be preserved in many:¹ therefore, even in incorruptible bodies there is but one individual in one species. Now the nature of a separate substance can be preserved in one individual, since they are incorruptible, as we proved above.² Therefore, there is no need for several individuals of the same species in those substances.

Again. In each individual, that which belongs to the species is more noble than that which is the principle of individuality, existing apart from the specific nature. Consequently, the multiplicity of species adds more nobility to the universe than the multiplicity of individuals of one species. Now, the perfection of the universe applies especially to separate substances. Therefore, it is more in keeping with the perfection of the universe that they should be many differing in species than that they should be multiplied numerically within the same species.

That the separate substance and the soul are not of one species

Furthermore, it can be proved from the foregoing that the soul is not of the same species with separate substances.

For there is a greater difference between the human soul and a separate substance than between one separate substance and another. Now, separate substances are all specifically distinct from one another, as we have proved.¹ Much more, therefore, is a separate substance specifically distinct from the soul.

Moreover. Each thing has its proper being according to its specific nature, because things which have a different kind of being have a different species. Now, the being of the human soul and that of a separate substance are not of the same kind, since the body cannot communicate in the being of a separate substance, whereas it can communicate in the being of the human soul, which is united in being to the body as form to matter. Therefore, the human soul differs in species from separate substances.

Again. That which is specified by itself cannot be of the same species as that which is not specified by itself but is part of a species. Now, the separate substance is specified by itself: whereas the soul is not, but is part of the human species. Hence it is impossible that the soul be of the same species as separate substances, except on the supposition that man be of the same species as they, which is clearly impossible.

How we are to understand genus and species in separate substances

It is necessary to consider wherein species differ in separate substances. For in material things of the same genus and differing in species, the ratio of the genus is derived from the material principle, and the specific difference from the formal principle. Thus the sensitive nature, from which is derived the ratio of animal, is material in man with respect to the intellective nature, from which is derived the specific difference of man (namely, rational). Consequently, if separate substances are not composed of matter and form (as is evident from what has been said),¹ it is not clear how we are to ascribe to them genus and specific difference.

Accordingly, it must be observed that the various species of things possess the nature of being in degrees. For in the first division of being we immediately find something perfect (namely, substantial being and actual being) and something imperfect (namely, accidental being and potential being). In like manner, if we run through the various species, we find that one species has an additional grade of perfection over another: for instance, animals over plants, and animals endowed with locomotion over those that are immovable. Again, in colors one species is seen to be more perfect than another, according as it approaches to whiteness. Hence Aristotle says that the definitions of things are like a number, the species of which is changed by the subtraction or addition of unity:¹ in the same way as in definitions, a different species results if a difference be removed or added.

Therefore, the ratio of a determinate species consists in the common nature being placed in a determinate degree of being. And since in things composed of matter and form, the form is like the term, and that which is determined by it is the matter or something material, it follows that the ratio of the genus must be taken from the material element, and the specific difference from the formal. Hence there results one thing from difference and genus, even as from matter and form. And just as it is one and the same nature that results from matter and form, so the difference does not add an extraneous nature to the genus, but is a determination of the generic nature itself: for instance, if we take as a genus “an animal with feet,” a difference of it will be “an animal with two feet,” which difference clearly adds nothing extraneous to the genus.

It is, therefore, evident that it is accidental to the genus and difference that the determination denoted by the difference be caused by a principle other than the generic nature, since the nature signified by the definition is composed of matter as determined, and form as determining. Hence if there be a simple nature, it will be determined by itself, nor will it need to have two parts, one determining and the other determined. Consequently, the ratio of genus will be derived from the ratio of its nature, and its specific difference will be derived from its determination, in that it is placed in a determinate grade of being.

It also follows from this that if any nature be without limits and infinite in itself, as we have shown to be the case with the divine nature,¹ we cannot ascribe to it either genus or species: and this agrees with what we have proved about God.²

Moreover, since the difference of species is attributed to separate substances according as various degrees are ascribed to them, and since there are not several individuals in one species,¹ it is clear from what has been said that no two separate substances are equal in degree, but that one is naturally above another. Hence it is stated: Do you know the order of the heavens? (Job 38:33). And Dionysius says² that even as in the whole multitude of angels there is a supreme, middle, and lowest hierarchy, so in each hierarchy there is a highest, a middle, and a lowest order, and in each order, highest, middle, and lowest angels.

By this is excluded the opinion of Origen,¹ who said that all spiritual substances were created equal from the beginning, among which he reckoned even souls; and that the difference which we find among these substances—in that this one is united to a body, and that one not, that this one is higher and that one lower—results from a difference of merits. For we have shown that this difference of degree is natural; that the soul is not of the same species as separate substances,² nor the separate substances themselves of the same species with one another; and that they are not equal in the order of nature.

That separate substances do not gather their knowledge from sensibles

From what has been laid down it may be shown that separate substances do not receive intellective knowledge from sensible things.

For sensibles by their very nature are adapted to be apprehended by the sense, as intelligibles by the intellect. Therefore, every substance that is capable of knowledge and derives that knowledge from sensibles is endowed with sensitive cognition, and consequently has a body united to it naturally, since sensitive knowledge is impossible without a bodily organ. But separate substances have not a body naturally united to them, as we proved above.¹ Therefore, they do not derive intellective knowledge from sensible things.

Moreover. A higher power must have a higher object. Now the intellective power of a separate substance is higher than that of the human soul, since the human soul’s intelligence is the lowest in the order of intellects, as we proved above.¹ And the object of the human soul’s intelligence is a phantasm, as stated above,² and this is higher in the order of objects than a sensible thing existing outside the mind, as appears from the order of cognitive powers. Consequently, the object of a separate substance cannot be a thing existing outside the mind as the direct object from which it derives its knowledge, nor can it be a phantasm. It follows, in consequence, that the object of the separate substance’s intellect is something higher than a phantasm. Now, nothing is higher than a phantasm in the order of knowable objects, save that which is intelligible actually. Therefore, separate substances do not derive intellectual knowledge from sensibles, but they understand things which are intelligible even in themselves.

Again. The order of intelligibles is in accordance with the order of intellects. Now in the order of intelligibles, things intelligible in themselves are above those things which are not intelligible but for the fact that we make them intelligible. Such must be all intelligibles taken from sensibles, because sensibles are not in themselves intelligible. But such are the intelligibles which our intellect understands. Therefore, the intellect of the separate substance, since it is above our intellect, does not understand intelligibles received from sensibles, but it understands those which are intelligible actually.

Moreover. The mode of a thing’s proper operation is in keeping with the mode of that thing’s substance and nature. Now a separate substance is an intellect existing by itself and not in a body. Consequently, its intellectual operation will be directed to intelligibles that are not founded on a body. But all intelligibles taken from sensibles are somewhat founded on bodies: for instance, our intelligibles are founded on the phantasms, which are in bodily organs. Therefore, separate substances do not derive knowledge from sensibles.

Further. Just as prime matter is the lowest in the order of things sensible, and is consequently only in potency to all sensible forms, so the possible intellect, being the lowest in the order of things intelligible, is in potency to all intelligibles, as is clear from what has been said.¹ Now those things which are above prime matter in the order of sensibles have their form actually, by which they are established in sensible being. Therefore, separate substances, which are above the human possible intellect in the order of intelligibles, are actually in intelligible being: for the intellect that receives knowledge from sensibles is in intelligible being not actually, but potentially. Therefore, a separate substance does not receive knowledge from sensibles.

Again. The perfection of a higher nature does not depend on a lower nature. Now the perfection of separate substances, since they are intellectual, consists in understanding. Therefore, their understanding does not depend on sensible things in such a way as to derive knowledge from them.

Hence it is evident that in separate substances there is not an active and a possible intellect, except perhaps in an equivocal sense. For a possible and an active intellect are found in the intellective soul insofar as it derives its knowledge from sensibles, since it is the active intellect that makes the species received from sensibles to be actually intelligible, and the possible intellect is that which is in potency to the knowledge of all forms of sensible things. Therefore, since separate substances do not derive their knowledge from sensibles, there is not in them an active and a possible intellect. Hence Aristotle, in establishing the possible and active intellects, states that we need to place them in the soul.¹

It is also evident that in these same substances, local distance cannot hinder the knowledge of separate substances. For local distance is essentially referable to sense, and not to the intellect except accidentally (insofar as it receives from sense, because sensibles move the senses at a determinate distance). Now things intelligible actually are not in place insofar as they move the intellect, for they are separate from corporeal matter. Since, then, separate substances do not derive intellective knowledge from sensibles, local distance has no effect on their knowledge.

Again, it is clear that time has nothing to do with their intellectual operation. For just as things actually intelligible are apart from place, so are they apart from time: because time is consequent upon local movement; therefore, it measures only such things as are somehow in place. Consequently, the understanding of a separate substance transcends time: whereas time touches our intellectual operation, since we derive our knowledge from phantasms, which relate to a determinate time. Hence it is that in composition and division our intellect always includes time past or future, but not in understanding what a thing is. For it understands what a thing is by abstracting intelligibles from sensible conditions: therefore, in respect of that operation, it understands the intelligible apart from time and all conditions of things sensible. But it composes and divides by applying previously abstracted intelligibles to things, and in this application time must be implied necessarily.

That the intellect of a separate substance always understands actually

From the foregoing it is also clear that the intellect of a separate substance always understands actually.

For that which is sometimes in act and sometimes in potency is measured by time. But the intellect of a separate substance transcends time, as we have proved.¹ Therefore, it is not sometimes actually understanding and sometimes not.

Moreover. Every living substance exercises actually some operation by virtue of its nature, although other operations are in it potentially: thus animals are always in the process of nourishment, although they do not always sense. Now, separate substances are living substances, as is clear from what has been said;¹ and they do not have another operation other than understanding. Therefore, by their nature they must be always actually understanding.

Again. The separate substances, according to the teaching of philosophers, move the heavenly bodies by their intellect. Now the movement of the heavenly bodies is always continuous. Therefore, the understanding of separate substances is continuous and perpetual.

The same conclusion follows even if we deny that they move the heavenly bodies, since they are higher than the heavenly bodies. Therefore, if the proper operation of a heavenly body, which is its movement, is continuous, much more will the proper operation of separate substances (namely, understanding), be continuous.

Moreover. Whatever sometimes operates and sometimes does not operate is moved either essentially or accidentally. Therefore, the fact that we are sometimes understanding and sometimes not understanding is due to an alteration in the sensible faculty, as stated in Physics 8.¹ But separate substances are not moved essentially, since they are not bodies; nor are they moved accidentally, since they are not united to bodies. Therefore, their proper operation, which is to understand, is continual in them without any interruption.

How one separate substance understands another

If separate substances understand things that are by themselves intelligible, as we have proved;¹ and if separate substances are by themselves intelligible, since freedom from matter makes a thing intelligible by itself, as appears from the foregoing,² it follows that separate substances understand separate substances as their proper objects. Therefore, each of them knows itself and others.

Each one indeed knows itself otherwise than the possible intellect knows itself. For the possible intellect is in potency in intelligible being, and is made actual by the intelligible species, even as prime matter is made actual in sensible being by a natural form. Now nothing is known according as it is only in potency, but according as it is in act; hence the form is the principle by which we know the thing which is made actual thereby, and in like manner the cognitive power is made actually cognizant by some species. Accordingly, our intellect does not know itself except by the species by which it is made actual in intelligible being, for which reason Aristotle says that it is knowable in the same way as other things,¹ namely, by species derived from phantasms, as by their proper forms. On the other hand, separate substances exist actually in intelligible being by their nature. Therefore, each one of them knows itself by its essence, and not by the species of another thing.

Since, however, all knowledge is according as the image of the thing known is in the knower, and since one separate substance is like another as regards the common generic nature, while they differ the one from the other in regard to the species, as appears from the foregoing;¹ it would seem to follow that the one does not know the other as regards its proper specific nature, but only as regards the common nature of their genus.

Accordingly, some¹ say that one separate substance is the efficient cause of another. Now in every efficient cause there must be the image of its effect, and likewise in every effect there must be the likeness of its cause, because every agent produces its like. Hence in the higher separate substance there exists the likeness of the lower, as in the cause there is the likeness of its effect; while in the lower there is the likeness of the higher, as in the effect there is the likeness of its cause. Now if we consider non-univocal causes, the likeness of the effect exists in the cause in a more eminent manner, and the likeness of the cause is in its effect in a less eminent manner. And the higher separate substances must be causes of this kind with respect to the lower separate substances, because they are placed in various degrees which are not of one species. Therefore, a lower separate substance knows a higher according to the mode of the substance knowing, and not according to the mode of the substance known, but in a lower manner: whereas the higher knows the lower in a more eminent way. This is the meaning of the statement in The Book of Causes, that an intelligence knows what is below it, and what is above it, according to the mode of its substance: because the one is the cause of the other.²

But since we have shown above¹ that intellectual separate substances are not composed of matter and form, they cannot be caused except by way of creation. Now to create belongs to God alone, as we proved above.² Therefore, one separate substance cannot be the cause of another.

Hence, according to the foregoing, each of the separate substances knows God by its natural knowledge, according to the mode of its substance, whereby they are like God as their cause. But God knows them as their proper cause, having in himself the likeness of them all. Yet one separate substance is unable to know another in this way, since one is not the cause of another.

We must, therefore, observe that since none of these substances according to its essence is an adequate principle of the knowledge of all other things, it is necessary for each of them, in addition to its own substance, to have some intelligible images by which each of them is enabled to know another in its proper nature.

This can be made clear in the following manner. The proper object of an intellect is an intelligible being, and this includes all possible differences and species of being: because whatever can be, is intelligible. Now, since all knowledge is caused by some kind of likeness, the intellect is unable to know its object wholly, unless it has in itself the likeness of all being and of all its differences. But such a likeness of all being can only be an infinite nature, which is not confined to any species or genus of being, but is the universal principle and active force of all being: and this is the divine nature alone, as we proved in the first book.¹ And every other nature, since it is confined to some genus or species of being, cannot be a universal likeness of all being. It follows, therefore, that God alone knows all things by his essence, while every separate substance knows its own species alone with a perfect knowledge by its nature. But the possible intellect does not know itself at all in this way, but by its intelligible species, as stated above.²

Now from the very fact that a particular substance is intellectual, it is capable of understanding all being. Therefore, as a separate substance is not made actually to understand all being by its nature, that substance considered in itself is as in potency to the intelligible images by which all being is known, and these images will be its acts insofar as it is intellectual. But it is not possible that these images be otherwise than several: for it has been already proved that the perfect image of the whole universal being cannot but be infinite; and just as the nature of a separate substance is not infinite, but limited, so an intelligible image existing in it cannot be infinite, but is confined to some species or genus of being; thus several such images are requisite for the comprehension of all being. Now, the higher a separate substance is, the more is its nature similar to the divine; consequently it is less limited, as approaching nearer to the perfection and goodness of the universal being, and for this reason it has a more universal participation of goodness and being. Consequently, the intelligible images that are in the higher substance are less numerous and more universal. This agrees with the statement of Dionysius¹ that the higher angels have a more universal knowledge: and it is said in The Book of Causes that the higher intelligences have more universal forms.² Now, the highest point of this universality is in God, who knows all things by one (namely, his essence); but the lowest is in the human intellect, which, for each intelligible object, requires an appropriate intelligible species commensurate with that object.

It follows that with the higher substances, knowledge through more universal forms is not more imperfect, as it is with us. For through the image of animal, by which we know something only in its genus, we have a more imperfect knowledge than through the image of man, by which we know the complete species, since to know a thing as to its genus only is to know it imperfectly and as potentially, whereas to know a thing as to its species is to know it perfectly and actually. Now our intellect, since it obtains the lowest place in intellectual substances, requires images particularized to that extent that there must correspond a proper image in it to each proper object of its knowledge: therefore, by the image of “animal” it does not know “rational,” and consequently neither does it know “man,” except in a certain respect. On the other hand, the intelligible image that is in a separate substance is of more universal virtue, and suffices to represent more things. Consequently, it argues not a more imperfect but a more perfect knowledge: because it is virtually universal, like the active form in a universal cause which, the more universal it is, the greater the extent of its efficiency, and the more efficacious its production. Therefore, by one image it knows both animal and the differences of animal: or again it knows them in a more universal or more limited way according to the order of the aforesaid substances.

Therefore, as we have stated, we may take examples of this in the two extremes, namely, in the divine and human intellects. For God knows all things by one thing (namely, his essence), while man requires different likenesses to know different things. Moreover, the higher his intellect, the more things is he able to know through fewer: therefore, we need to give particular examples to those who are slow of intelligence so they acquire knowledge about things.

Now, since a separate substance, considered in its nature, is in potency to the images by which all being is known, we must not think that it is devoid of all such images: for such is the disposition of the possible intellect before it understands, as stated in On the Soul 3.¹ Nor again must we think that it has some of them actually, and others only potentially: even as prime matter in the lower bodies has one form actually and others potentially; and as our possible intellect, when we are already possessed of knowledge, is in act in respect of some intelligibles, and in potency in respect of others. For, since these separate substances are not moved, neither essentially nor accidentally, as we have proved,² whatever is potential in them must be actual, or else they would pass from potency to act, and thus they would be moved essentially or accidentally. There is, therefore, potency and act in them as regards intelligible being, just as there is in the heavenly bodies as regards natural being. For the matter of a heavenly body is so perfected by its form that it does not remain in potency to other forms: in like manner the intellect of a separate substance is wholly perfected by intelligible forms with respect to its natural knowledge. On the other hand, our possible intellect is proportionate to the corruptible bodies to which it is united as a form: because it is made to have certain intelligible forms actually in such a way that it remains in potency to others. For this reason it is stated in The Book of Causes that an intelligence is full of forms,³ namely, since the whole potency of its intellect is perfected by intelligible forms. And thus one separate substance is able to understand another through these intelligible forms.

Someone, however, may think that, since a separate substance is intelligible by its nature, there is no need to assert that one is understood by another through intelligible species, but that they understand one another by the very essence of the substance understood. For it would seem that the fact of a substance being understood through an intelligible species is accidental to material substances, from their not being actually intelligible through their essence: therefore, it is necessary for them to be understood through abstract intentions. Moreover, this seems in accord with the statement of the Philosopher who says that in separate substances there is no distinction between matter, intellect, the act of understanding, and the thing understood.¹

And yet if this be granted, it involves not a few difficulties. First, because the intellect in act is the thing understood in act according to the teaching of Aristotle:¹ and it is difficult to see how one separate substance is identified with another when it understands it.

Again. Every agent or operator acts through its form, to which its operation corresponds (as heating corresponds to heat). Hence we see the thing whose species informs the sight. Yet it does not seem possible for one separate substance to be the form of another, since each has its being separate from the other. Therefore, it seems impossible for the one to be seen by the other through its essence.

Moreover. The thing understood is the perfection of the one who understands. Now a lower substance cannot be a perfection of a higher. It would follow, therefore, that the higher would not understand the lower, if each were understood through its essence and not by another species.

Further. The intelligible object is within the intellect as to that by which it is understood. Now no substance enters into the mind save God alone, who is in all things by his essence, presence, and power. Therefore, it is seemingly impossible for a separate substance to be understood by another through its essence, and not through its image in that other.

This must indeed be true according to the opinion of Aristotle, who says that understanding takes place through the fact that the thing understood in act is one with the intellect in act. Therefore, a separate substance, although it is by itself actually intelligible, is nevertheless not understood in itself except by an intellect with which it is one. And it is thus that a separate substance understands itself by its essence: so that, according to this, the intellect, the thing understood, and the act of understanding are the same thing.

But according to the opinion of Plato, understanding takes place through contact of the intellect with the thing understood. So that, in consequence, one separate substance can understand another through its essence when it is in spiritual contact with it: the higher understanding the lower as though by enclosing and containing it by its power, and the lower understanding the higher as though it grasped it as its own perfection. Hence Dionysius says¹ that the higher substances are intelligible as the food of the lower substances.

That separate substances know material things

By these aforesaid forms, then, a separate substance knows not only other separate substances, but also the species of corporeal things.

For, since their intellect is perfect in respect of its natural perfection, being wholly in act, it follows that it comprehends its object, intelligible being, in every respect. Now intelligible being comprises also the species of corporeal things. Therefore, a separate substance knows them.

Again. Since the species of things are differentiated as the species of numbers, as stated above,¹ it follows that the higher species contains in some way that which is in the lower, even as the greater number contains the lesser. Seeing, then, that separate substances are above corporeal substances, it follows that whatever is contained in corporeal substances materially is contained in separate substances intelligibly; for that which is in a thing is there according to the mode of the thing in which it is.

Again. If the separate substances move the heavenly bodies, as philosophers say, whatever results from the movement of the heavenly bodies is ascribed to those same bodies as instruments, since they move through being moved; and to the separate substances that move them, as principal agents. Now they act and move by their intellect. Consequently, they cause whatever is done by the movement of the heavenly bodies just as the craftsman works through his tools. Hence their forms which are generated and corrupted are in separate substances intelligibly. Therefore, Boethius, in his book De Trinitate, says that from forms that are without matter came the forms that are in matter.¹ Therefore, separate substances know not only separate substances, but also the species of material things. For if they know the species of bodies subject to generation and corruption as being the species of their proper effects, much more do they know the species of heavenly bodies as being the species of their proper instruments.

Therefore, since the intellect of a separate substance is in act (having all the images to which it is in potency), and since it has the power to comprehend all the species and differences of being, it follows of necessity that every separate substance knows all natural things and their whole order.

Yet, seeing that the intellect in act is the thing actually understood,¹ someone might think that a separate substance does not understand material things, for it would seem incongruous that a material thing should be the perfection of a separate substance.

But if the point be considered aright, the thing understood is a perfection of the one who understands according to its image in the intellect, for the stone which is outside the soul is not a perfection of our possible intellect. Now the image of the material thing is in the intellect of a separate substance immaterially, according to the mode of a separate substance, and not according to the mode of a material substance. Therefore, there is no reason why we should not say that this image is a perfection of the separate substance’s intellect, as its proper form.

That separate substances know singulars

Since in the intellect of a separate substance the images of things are more universal than in our intellect, and more efficacious as a medium of knowledge, it follows that separate substances, through the images of material things, know material things not only according to their generic or specific nature, but also according to their individual nature.

For seeing that the species of things in the intellect must be immaterial, they cannot, as existing in our intellect, be the principle of knowing singulars, which are individualized by matter: because the species of our intellect are of such limited power that one leads to the knowledge only of one. Therefore, just as the image of the generic nature cannot lead to the knowledge of genus and difference, so that the species be known thereby, in like manner the image of the specific nature cannot lead to the knowledge of the principles of individuality, which are material principles, so that the individual be known by it in its singularity. On the other hand, the image in the intellect of a separate substance is able to lead to the knowledge of both the specific and the individualizing principles, since it is of a more universal power (being at the same time one and immaterial), so that through it the separate substance is able by its intellect to know not only the generic and specific natures, but also the individual nature. Nor does it follow that the form through which it knows is material; nor that such forms are infinite according to the number of individuals.

Further. Whatever a lower power can do, a higher power can do in a higher way. Hence the lower power works by many instruments, whereas the higher power works by one only. For the higher a power is, the more is it consolidated and unified; but on the other hand, the lower power is disunited and multiplied. Hence we observe that the one power of the common sense apprehends the various kinds of sensibles which the five external senses perceive. Now the human soul is lower than a separate substance in the order of nature: and it is cognizant of universals and singulars through two principles, namely, sense and intellect. Consequently, a separate substance, being higher, knows both in a higher way by one principle, namely, the intellect.

Again. The order in which the intelligible species of things reach our intellect is contrary to the order in which they reach the intellect of a separate substance. For they reach our intellect by a process of analysis, and by abstraction from material and individualizing conditions, so that it is not possible for us to know singulars through them. On the other hand, they reach the intellect of a separate substance as by a process of synthesis, since it has intelligible species through its likeness to the first intelligible species, namely, the divine intellect, which is not abstracted from things, but productive of them. Now, it is productive not merely of the form but also of the matter, which is the principle of individuality. Therefore, the species of the intellect of a separate substance represent the whole thing not only the principles of its species, but also the principles of its individuality. Consequently, we must not deny separate substances the knowledge of singulars, although our intellect is unable to know singulars.

Now since the intellect in act is the thing actually understood, as the sense in act is the thing actually sensed,¹ and since the same thing cannot be several things actually at the same time, it would seem impossible for the intellect of a separate substance to have various species of things intelligible, as we have stated above.²

But it must be noted that not everything whose intelligible species is actually in the intellect is actually understood. For, since a substance which has understanding also has a will (and consequently has the control of its action), when it already has an intelligible species, it is in its power to make use of it for understanding actually, or, if it have several species, to use one of them. Therefore, we do not actually consider all the things of which we possess knowledge. Therefore, an intellectual substance that has knowledge through several species uses one of them as it will, and thereby knows actually at the same time all that he knows by one species; for they are all as one intelligible thing insofar as they are known through one (species), even as our intellect knows at the same time several things compared or related to one another as one individual thing. But it does not know at the same time the things which it knows through different species. Therefore, as there is one understanding, so is there one thing actually understood.

Accordingly, in the intellect of a separate substance there is a certain succession of understandings: there is not, however, movement properly speaking, since act does not succeed potency, but act succeeds act.

But the divine intellect, because as it knows all things through one (namely, the divine essence), and because its act is its essence, knows all things at the same time.

Consequently, there is no succession in his understanding, but his act of intelligence is wholly perfect at the same time, and endures through all ages. Amen.