Commentaria in Summam contra Gentiles, Liber II

To these arguments ¹ a reply is given according to the mind of Averroes.

I. And it is said first that man differs from the brutes not by the possible intellect, but by the passive intellect, which is the cogitative power in man, in place of which the brutes have the estimative power.

It is said second, that it belongs to this power to distinguish particular intentions and to compare them with one another; and, together with the imaginative and memorative powers, to prepare the phantasms so that they may be made actually intelligible by the agent intellect. From this it comes about that it is called by the name of intellect and reason, namely, that it is called passive intellect and particular reason. It belongs also to this same power to acquire for itself, through use and exercise, the habits of the sciences.

It is said third, that this passive intellect is present in the child from the beginning, and through it the child acquires the human species, even before it actually understands.

But it must be noted that by the name of individual intentions are understood particular forms insofar as there are found in them certain conditions that do not fall under the exterior sense: such as friendship, enmity, the useful and the harmful, and the like. For these are known through the estimative power in brute animals, and through the cogitative power in man. Thus a sheep, judging the wolf to be an enemy, flees; but it does not flee another sheep, because it reckons it a friend; and so it makes a distinction and comparison between the sheep and the wolf. Similarly, a bird gathers straw, because it judges it useful for building its nest; but it does not gather a twig, because it judges that useless. What brutes do through the estimative power, men do through the cogitative power, and far more perfectly, since they also compose particular propositions by means of it—something brutes do not do, but only apprehend friendship and enmity and the like in things.

II. Against this answer, however, Saint Thomas argues in several ways.

First ². Man has an operation proper to himself above the other animals, namely to understand and to reason, as is shown in I Ethics. Therefore one must posit in man some part of the soul which properly gives the species to man, and which stands to understanding as first act to second act. Therefore it cannot be by the passive intellect that man receives his species, whereby he differs from the other animals. — The first consequence is proved: because the operations of life are compared to the soul as second acts to a first, as is clear in II De Anima. But the first act precedes the second act in time within the same subject, just as knowledge precedes considering. — The second consequence is also proved: because the principle of intellection cannot be the passive intellect, since the principle of such an operation must be impassible and unmixed with the body, as the Philosopher proves; the contrary appears in the case of the passive intellect, to which, namely, the middle cell of the head is assigned as its seat.

2. Concerning this proposition, "The first act precedes in time the second act in the same thing," a doubt is raised. Because a heavy body, as soon as it is generated, begins to move unless an impediment is present. And a luminous body illuminates immediately, when an unobstructed diaphanous medium is present.

It is answered that this proposition has truth where the second act does not follow from the first act by natural necessity: as is the case at hand, where the act of understanding does not necessarily follow, given that the intellective principle exists in matter.

It can be answered secondly that Saint Thomas is speaking of the possible: namely, that the first act can precede the second act in time. And this is said in conformity with what is found in Ia IIae, q. 3, a. 2, where Saint Thomas says that one who has a form can be in potency with respect to operating, just as one who knows is in potency with respect to considering. And this suffices for Saint Thomas's purpose. For he wishes to gather from this that the first act and the second must be in the same thing. Which is clearly obtained if, in the same thing, the first act sometimes precedes the second not only in nature but also in time.

III. But to this argument one could reply in two ways. First, that according to the principles of St. Thomas it does not follow: as Scotus seems to say, IV Sent., d. XLIII, q. II ³. For in St. Thomas the intellect and understanding are related passively, not actively. And therefore the operation of understanding does not come from the soul, but from the intelligible object or from the phantasm.

Second, that understanding is indeed the proper operation of man, but not intrinsic to him. For it belongs to every man and to him alone through his continuity with the possible intellect, but not through the form by which he is ultimately constituted in being, since man is constituted in being by the cogitative power. And therefore there need not be in man a first act corresponding to this operation as giving him esse. And that proposition—"In whatever is found some operation of life, one must posit in it some part of the soul which is related to it as first act is related to second act"—is true only where the operation is posited in something as intrinsic to it, namely as proceeding from its completing form.

2. To the first of these responses it is said, first, that it is not the doctrine of Saint Thomas that the intellect merely passively concurs in intellection, even though the intellect is a passive power. For although it receives from the object itself the species by which it understands, on account of which it is said to be acted upon, and in respect of which consideration it is a passive power; yet, informed by the intelligible species, it produces the very act of intellection elicitedly, as is clear from De Veritate, q. 1, a. 9. Hence Scotus falsely imputes to us that the intellect and understanding are related merely passively and in no way actively.

It is said second that, even if it were granted that the intellect concurred in intellection merely passively, the argument of St. Thomas would still be effective. For if intellection is the proper operation of man, whether active or passive — for this is manifest, that intellection is present in man formally, and by means of it he surpasses the other animals — one must say that its proper recipient is formally in man: for act and the potentiality of that recipient belong to the same supposit. And thus it is fittingly argued that, from the fact that understanding is the proper operation of man, whether produced by him or received in him, the principle of that operation, whether productive or receptive, must be the form of man. And since this can be nothing other than the intellective soul, it follows that the intellective soul itself is the form of man.

3. Against the second reply it is argued, because the nature of each thing is known from its own specific operation: and from the fact that some operation belongs to a nature insofar as it is such, it can be argued that that thing receives its species through that which is the principle of that operation; otherwise there would be no way of knowing the natures of things from their operations. If, therefore, understanding is the proper operation of man, belonging to man insofar as he is man; and in which man's beatitude consists; and through which he transcends all other things; it is necessary that the principle of this operation be the form of man that gives him his species. For a proper and specific operation must proceed from a proper and specific form.

IV. Second, ⁴. Phantasia and the powers that follow upon it, such as memory and similar ones, are passions of the sensitive part, as is said in the book On Memory and Recollection. Therefore through them, or through any one of them, no animal can be placed in a higher genus of life than that of sensitive soul and sensitive life. Therefore man does not live a life proper to himself by virtue of the cogitative power. — The first consequence is proved: because a passion of the sensitive part cannot place one in a higher genus of life than that of sensitive life, just as neither does the nutritive place one in a higher genus of life than that of nutritive life. — The second is made manifest because man is in a higher genus of life than that of sensitive life, as is clear from the Philosopher in II de Anima, where he superadds the intellective, which he attributes to man, to the sensitive, which he attributes to every animal.

2. It will perhaps be said that, although the cogitative power taken absolutely does not place anything in a higher genus of life than sensitive life, it can nevertheless do so when it is joined to the intellect: because from such a union it has a certain nobility which it does not have when considered in itself.

But against this it is argued. First. Either that conjunction is understood by reason of the phantasm, or according to the relation of mover and moved. Not the first: because a child in the mother's womb is essentially a human being, and yet does not have the cogitative union with the intellect, which is by reason of the phantasm. Not the second: because from the fact that one is the mover of the other, it does not have the perfection by which it could constitute something essentially; for the union of the mover to the mobile presupposes the mobile itself. Therefore there is no answer.

Second. However much, through its union with the intellect, the cogitative power itself might acquire some perfection, it is nevertheless never raised so high as to be above the sensitive part. Therefore, from its union with the intellect it cannot place anything in a higher degree of life than that of sensitive life.

V. Thirdly, in the principal argument. Man is a self-mover, just as the other animals are. Therefore the mover and the moved are parts of him. Therefore the intellect. — The first consequence is proved from Physics VIII. — The second, however, is proved because the first mover in man is the intellect, since it moves the will by means of its intelligible object.

If it is said that this suffices for moving the passive intellect: the contrary is argued. For the passive intellect is only of particulars; but in moving, there is taken, besides this, universal opinion, which belongs to the possible intellect; as is clear in III de Anima, text. 58, and VII Ethic., ch. V⁵.

2. To this argument the Averroists could respond in two ways. First, that the first mover of man need not be a part of him, but it suffices that it be fitted to him as his proper mover: just as the heaven is said to move itself, and yet the intelligence moving the body of the heaven is not a part of it, but is only united to it as its proper mover.

Second, that Aristotle's mind is that the mover, in the manner of an efficient cause, is a part of the self-mover; but not a mover in the manner of a final cause. Now, the intellect does not move in the manner of an efficient cause, but only in the manner of a final cause, as presenting the object to the will.

3. But against the first response it is argued. It is not intelligible that something move itself, unless it is said either that the whole moves the whole, or that a part moves a part, in such a way that the whole, by reason of one part, is mover and by reason of the other part moved. But from the fact that something extrinsic to its substance moves it, however appropriate a mover it may be to it, that thing is not said to move but to be moved: hence neither is a part of an animal moved by another part said to move the animal, however appropriate the moving part may be as its mover. Therefore the response is worthless. — Nor does the objection concerning the heavens avail. For if the heaven is posited to move itself, it is not said to move itself by reason of the abstract intelligence, but by reason of its soul; for, given that supposition, one must posit that the heaven is truly ensouled, as St. Thomas will show below ⁶.

If it is said that man can be named either as constituted by the cogitative power alone, or as an aggregate of that and the intellect; and that in the first way he does not move himself completely, but only as taken in the second way: it is argued against this. First, because man moves himself no less than other animals do. But other animals, considered according to their essence alone, move themselves. Therefore man too, considered substantially with respect to his essential parts alone, is a self-mover. — Second, because man, taken in the second way, does not signify one thing simply and per se: since intellect and man are not substantially undivided; for they do not share in one substantial esse.

4. That the second reply is empty is evident. For when the Philosopher, in II de Anima ⁷, posited that the mover with respect to place is a part of the soul, in III ⁸, inquiring into this principle, he holds that intellect and appetite are the movers in man, and that intellect and appetite have the character of one mover. From this it clearly appears that he does not exclude intellect from the motive power that is a part of the soul, however we take intellect to move, whether, I say, by way of end or by way of efficient cause. Above, however, ⁹ it has been shown how intellect moves.

VI. Fourth. The will of man is in the intellective part. And it is not extrinsic to man as a separate substance, but is in man himself. Therefore the possible intellect must be in us, by which we differ from brute animals, not only according to the passive intellect.

The major premise is proved. Because the will cannot be the act of any body, nor follow upon any power that is the act of some part of the body. This is evident, first, because it can extend itself to the universals of all sensible forms: for of all things that we understand we can have a will, at least with respect to knowing them; and it is also borne toward the universal of its own act, as when we hate in the universal the class of thieves, as Aristotle says in his Rhetoric. Now every part of the soul is the act of some body except intellect properly so called. — Second, because it is said in book III of De Anima that the will is in reason, while the irascible and concupiscible powers are in the sensitive part. Hence also the act of the will occurs with choice, but not with passion.

The minor premise is also proved. For otherwise man would not be the lord of his own operations, since he would be acted upon by the will of some separate substance. Which is destructive of the whole of moral philosophy and of political life.

2. Concerning that proposition, "Of all things we understand we can have a will, at least for knowing them," it must be noted what Saint Thomas adds, "at least for knowing them," because, since the will does not follow the speculative intellect but the practical, as is said in III De Anima ¹⁰; someone could say that many things are understood by us toward which the will is not borne, namely those which are wholly speculative. But, this being granted, nevertheless it cannot be denied that concerning things which cannot be produced by the work of the intellect, there can be some act apprehended under the aspect of good or fittingness, and consequently belonging to the practical intellect: as it is to consider and to understand. For although "a triangle having three angles" does not have in itself the aspect of the appetible or avoidable, yet knowledge of it can have the aspect of good and fitting: and thus, although the will does not desire a triangle having three angles, it can nevertheless desire cognition of it, proposed to it by the intellect under the aspect of good and appetible. And consequently we can have a will for all things we understand, by desiring them at least with respect to their cognition.

VII. Fifth. A child is intelligent in potency. Therefore in him there is some potency by which he is able to understand. Therefore the possible intellect is joined to the child before he understands. Therefore the possible intellect is not united to man through a form understood in act, but is present in him from the beginning as something of his own. — The first inference is proved: for just as nothing can act except by an active power existing in it, so nothing is able to be acted upon except by a passive power that is in it, as is clear in the case of what is combustible. — The second is also proved: because the possible intellect is that power by which man is able to understand and to be acted upon by the intelligible.

2. To this argument Averroes responds, in the third book of De Anima, that a child is said to be in potency to understand in two ways: namely, because the phantasms which are in him are in potency intelligible; and because the intellect can be conjoined with him, but not because it is united with him.

3. Against the first part of this reply, St. Thomas argues first ¹¹, because for the phantasms to be able to be understood in act in a child is to be able to act. Therefore a child is not said to be able to understand on the ground that phantasms in him can be understood in act. — The antecedent is proved: because phantasms move the possible intellect. — The consequence is also proved: because to be able to understand is to be able to be acted upon. But that by which it belongs to someone that he can act does not belong to him as being able to be acted upon.

To make the antecedent evident, it must be considered that the species understood in act, when joined to the possible intellect, is not said to be in potency in the phantasm as though the phantasm were the receptive potency of that species, so that it would be said to be in it as in a passive potency; but because the phantasm can, together with the agent intellect, cause that species in the possible intellect. For the phantasm is compared to the possible intellect as an object to a power, as Saint Thomas says below ¹². Now the object of the intellect is its mover, since the intellect is a passive power. Hence in the preceding chapter Saint Thomas said that phantasms are made actually intelligible by the light of the agent intellect, so that they may move the possible intellect. Therefore it is rightly said here in the antecedent that phantasms are able to be understood in act, and that this pertains to being able to act; for they are not said to be able to be understood in act as though the phantasm itself, one and the same in number, could be stripped of its material conditions and inform the possible intellect; but because it can cause in the possible intellect a form stripped of material conditions, by which the intellect is actually able to understand.

Concerning that proposition, "To be able to understand is to be able to be acted upon," it must be noted that this is understood of the power to understand in the first and essential sense, according as one who does not have an intelligible form in act is said to be able to understand on account of the intellective power alone existing in him; but not of the power to understand in the accidental sense, according as one existing in a habit is said to be able to act. For since the possible intellect cannot understand unless it is informed by an intelligible species, when it is without such a species it can receive that species from the object and the phantasm. And thus to be able to understand is to be able to be acted upon: because it is the ability to receive a species from something intelligible, from which it can afterwards produce the act of intellection by way of an active principle. Hence, if the intellect is considered simply, stripped of every species, its power to understand is the very power to be acted upon and to receive; but if it is considered as already informed by a species, its power to understand is not the power to be acted upon, but the power to act, which is in some way to act.

But if someone were to say that the power to understand, even when the intellect is considered as informed by a species, is a power to be acted upon, because understanding is an immanent operation, one that is received in the agent, and thus the power to understand is the power to receive intellection: it is said that, although intellection is an operation received in the agent, it is nevertheless not received in the potency together with the intelligible species, but only in the intellective potency itself. Hence it does not follow that in the intellect informed by a species, as such, the power to understand is a power to receive and a power to be acted upon, but only in the intellect considered in itself and bare.

4. Second. The ability to understand follows upon the human species, since understanding is the operation of man insofar as he is such. Therefore it cannot be said that a boy is potentially understanding by reason of the phantasm. — The consequence is proved. Because a power following upon the species does not belong to something according to what does not bestow the species. But phantasms do not give the human species; rather they follow upon the operation of man.

5. Against the second part ¹³ he argues: and first thus. Someone is said to be able to act or be acted upon by means of a power, just as white is said through whiteness. But someone is not said to be white before whiteness is conjoined to him. Therefore someone cannot be said to be able to act or be acted upon before a power is present in him. Therefore a boy is not said to be able to understand before the intellect is continuous with him.

Second. The child is in potency as an intelligent being, not as though it did not yet have the nature of understanding, but rather as having an impediment such that it does not understand: for it is impeded on account of the manifold motions existing within it, as is clear from Physics VII. Therefore it is not said to be able to understand because the intellect could be continued to it, but because the intellect is united to it and is impeded from its proper act. — The antecedent is made evident by the multiple ways in which someone is said to be able to act.

VIII. Sixth, it is argued principally against another statement in the first reply ¹⁴, namely, that it belongs to the cogitative power to acquire for itself a habit of the sciences. To consider by understanding, which is the act of science, is not the act of the passive intellect, but of the possible intellect. Therefore the habit of science is not in the passive intellect, but in the possible. Therefore the possible intellect is in us, not as a separate being. — The antecedent is proved: because in order for any power to understand, it must not be the act of some body. — The first consequence is also proved: because habit and operation according to habit belong to the same subject, since a habit is that by which one operates when one wills. — The last consequence is also proved: because science is in us, by which we are said to be knowing.

Seventh. A thing known, insofar as it is known, is assimilated to the knower only according to universal species, since knowledge is of things of this kind, namely universals. Therefore knowledge is not in the passive intellect, but only in the possible intellect. Therefore etc. — The consequence is proved. Because the passive intellect is a power using an organ; but in such a power there cannot be universal species. — How intelligible species are universal was sufficiently shown above ¹⁵.

Eighth. The intellect in habit is an effect of the agent intellect, as Averroes himself confesses. Therefore the intellect in habit, which is a habit of knowledge, is in the possible intellect, not in the passive intellect. — The consequence is proved: because the effects of the agent intellect are intelligibles in act, whose recipient is the possible intellect, to which, according to Aristotle, III de Anima, text 17, the agent is compared as art to matter.

IX. Ninth. The perfection of the possible intellect depends on man's operation, since it depends on phantasms, which move the intellect. Therefore it is not a substance superior to man. Therefore it is something of man, as his act and form. — The first inference is proved: because it is impossible that the perfection of a superior substance depend on an inferior one. — As for the second inference, note that it holds according to the position of Averroes, who holds that the intellect is not the form of man precisely because it is a substance superior to man.

2. But to this argument one could reply, first, that its foundation is false. For man, both as regards sense and as regards intellect, is perfected by inanimate things, from which he receives the species of things knowable. And yet inanimate things are inferior to man according to substance. And thus it is not impossible that the perfection of a superior substance should depend upon an inferior one.

Second. Once that foundation is admitted, it could be said that it has truth concerning the dependence of the superior substance upon the inferior as upon a principal agent, but not as upon an instrument. For it is not unfitting that the superior substance be perfected instrumentally by the inferior.

3. To the first of these it is said that the foundation of the argument is true, if rightly understood. For by a superior substance Saint Thomas does not mean a substance superior in any manner whatever, but one that is of a higher order. For a substance of a higher order is never perfected by a substance of a lower order. For agent and patient must belong to the same order, or the agent must be of a higher order. For we see that corruptible bodies cannot act upon incorruptible bodies so as to perfect them, nor material substances upon immaterial ones, but quite the reverse. Hence the objection is not to the point. For although inanimate things are less perfect than animate ones, they nevertheless belong to the same order as man: for both man, who is perfected by inanimate things, and inanimate things themselves belong to the order of material things, among which man holds the highest place. From this it follows that, if Averroes posits the intellect as abstracted from man, as a substance of a higher order, it cannot be perfected by man, who according to him is of a lower order, being constituted in his own species by the cogitative power, which is a material faculty.

To the second it is said that neither can a substance of a higher order be perfected by an inferior one even instrumentally. For as Saint Thomas says in the Third Book of this work ¹⁶, that cannot be done through any instrument to which the action of that instrument cannot extend itself; otherwise determinate effects would not require determinate instruments. But a thing of the lower order cannot by its own action reach a thing of the higher order. Therefore, and so on. Hence also an intelligence does not use corruptible bodies for the alteration of incorruptible bodies; nor bodies for altering and perfecting another intelligence.

X. Tenth. The operation of the possible intellect needs the body: because, as is said in III De Anima, the intellect can understand only when it has been brought into act by a species abstracted from phantasms, which do not exist without the body. Therefore it is not wholly separate from the body. — The consequence is proved. Because whatever things are separate in esse have separate operations. This is evident, first, because things exist for the sake of their operations, as the first act exists for the sake of the second. And also from the conditional laid down by the Philosopher in I De Anima: namely, that if any operation of the soul is without the body, it is possible for that operation to be separated.

2. To this argument one could object that lower bodies cannot carry out their actions without the heavenly bodies: for when the motion of the heavens ceases, the natural motions of other bodies will cease as well, as St. Thomas holds ¹⁷. Similarly, an animal cannot sense without bodies from which it receives sensible species. And yet these are separate in their esse. Therefore it is not universally true that things separate in esse have separate operations, such that one does not depend on another in its operation.

It is answered that it is not the mind of St. Thomas that things which are separate in esse have operations so separate that one can in no way contribute to the operation of the other, as the objection proceeds; but rather that they have their own distinct operations, such that the operation of one is not that of the other as its proximate agent eliciting that action. For just as the esse of one is not the esse of another, so the proper operation of one is not that of another, since diverse forms are ordered to diverse operations. According to this sense, moreover, the argument of St. Thomas proceeds most fittingly. For if the intellectual substance, in respect of the possible intellect (for by the name of the possible intellect St. Thomas understands the substance endowed with such an intellect), were distinct in esse from the sensitive soul, whose function it is to form the phantasms, the operation of forming phantasms would not belong to such an intellectual substance as to a form proximately eliciting that operation. But this is false: for the intellectual form, which understands by abstraction from phantasms, must form for itself phantasms suited to understanding; for the intellectual form does not abstract from phantasms belonging to another, but from its own, as though illuminated by it so that from them an intelligible species might be abstracted. Therefore it is necessary that such an intellectual form and the sensitive soul agree in one esse; and since the sensitive soul, to which it belongs to form phantasms, is not separate from the body, because phantasy is not without the body, it is necessary that this intellectual form likewise not be separate from the body in esse.

XI. Eleventh. The operation of the possible intellect is completed through bodily organs, in which phantasms must exist. Therefore nature has united the possible intellect with bodily organs. Therefore, etc. — The first inference is proved from Aristotle, On the Heavens II, text 34: because to whatever belongs some operation by nature, those things without which that operation cannot be completed are attributed to it by nature.

It must be noted that this argument proceeds from the same foundation as the preceding one: namely, that the form, insofar as it is made cognitive by the possible intellect, must—before it exists in act through an intelligible species—form for itself phantasms from which it may abstract intelligible species. And since this cannot be done without bodily organs, in which the phantasms must exist, it is necessary that nature have united the possible intellect (that is, the very substance understanding with such an intellect, not the intellective power itself) to bodily organs.

Twelfth. It cannot understand substances wholly separate from matter, that is, according to their essence and quiddity. Therefore etc. — The antecedent is proved. Because this intellect understands nothing of this kind without a phantasm, as is said in III De Anima: since phantasms are related to the intellect as sensibles are to the sense. But there are no phantasms of such things. — The consequence is also proved. Because if the intellect were separate, it would understand separate substances more than sensible ones, since they are more intelligible and more conformable to it.

Thirteenth: and it is a confirmation of the antecedent of the preceding argument; as are the other arguments that follow. The agent intellect does not make intelligibles except through phantasms. Therefore neither is the possible intellect moved by other intelligibles except from species abstracted from phantasms. Therefore it cannot understand separate substances. — The first consequence is proved. Because in every genus passive power extends only as far as the active power of that genus. This is shown by this sign: because there is no passive power in nature to which there does not correspond some natural active power.

2. Concerning this proposition, "There is no passive potency in nature to which there does not correspond some natural active potency," a doubt is raised. First, because in matter there is a potency for the intellectual soul. And yet no natural agent can produce the intellectual soul.

Second, because matter which was under one form, that form having been corrupted, is in natural potency toward the same form, since the privation of this form in the matter is the same before it had the form and after it had it. And yet no natural agent can introduce that form into the matter, since it is impossible for what is one in number to be restored by a natural agent. Therefore, etc.

3. For the clarification of this, it must be considered that, although "natural" can be taken in many ways, in this context a natural power is that power which is ordered to something according to the inclination of created nature. Hence there is said to be in nature a passive power, or natural power, the power of a nature which has an innate inclination to receive from an external created source a natural form: just as prime matter is inclined to receive substantial form from some corporeal and material agent. An active natural power, however, is said to be a created virtue which has an innate inclination to act upon another creature. And just as every natural power, whether active or passive, determines for itself its proper object, of which it is receptive or productive, so a passive power determines for itself a proper agent from which it receives form; and an active power determines for itself a proper patient upon which it acts. Hence the sense of the proposition adduced, which is that of the Commentator on Metaphysics IX ¹⁸, is that there is no passive power inclined by the condition of nature to receive a natural form from another, to which as its proper agent there does not correspond some created active power, naturally inclined to act upon it. For since a natural passive power is ordered to receiving natural forms, and a natural form is one that can be produced by a natural and created agent, it is necessary that to a natural passive power there correspond some active natural power, as its proper agent from which it is by nature apt to receive a natural form.

4. To the first objection, therefore, it is said that in the way in which the intellectual soul is a natural form, in that same way matter is in natural potency to it, and a natural agent is its producer. For if it is considered with respect to its esse absolutely, then it is not a natural form but a supernatural one. And in that way prime matter is not in natural potency to it: for matter is said to be in natural potency with respect to the esse of a form absolutely when such a form is educible by a natural agent from the potency of matter; but the intellectual soul is not educible by a natural agent from the potency of matter, since it can remain separate from matter. If, however, it is considered with respect to its union with matter, then it is a natural form; and matter is in natural potency to it, namely insofar as it is unifiable with matter; and a natural agent is its cause, insofar as it causes in matter the dispositions disposing it to union with matter.

5. To the second it is said that matter is not in natural potency to the same numerically identical form which it lost: because that form, after it ceased to be in matter, is no longer a natural form. Hence that same form, before matter is actualized by it, is natural, inasmuch as it is producible into esse by a natural agent. But after, separated from matter, it has ceased to be or to be united to matter, it is supernatural, inasmuch as it is producible only by a supernatural agent. It is nevertheless called absolutely, according to the account of its species, a natural form: because, speaking absolutely, it is producible into esse by a natural agent.

In proof, it is said first that for matter to be in natural potency to a form, it does not suffice that it have the privation of the form, if by privation is understood only the negation of the form in matter; there is also required an aptitude and inclination of matter to the natural form. Therefore, although after the loss of the form there remains the same privation on account of the identity of term and subject, nevertheless there does not remain the same natural potency: because there does not remain the aptitude of matter to the form as to a natural form.

It is said second that, if by privation is understood the negation of a form in a subject apt to receive the form as natural, whether from a natural agent, then privation is not one in number before and after, on account of the variation of the subject's aptitude and inclination. For previously the matter was inclined toward it as toward a natural form; afterward, however, it no longer has that aptitude and inclination—although it is apt to receive that form from God, wherein consists the account of obediential power, not of natural power, properly speaking.

XIII. Fourteenth. If it were to understand immaterial substances, in them it would receive knowledge of sensible things: for in the separate substances there are intelligible species of sensible things, through which they have knowledge of sensibles. Therefore it would not receive that knowledge from phantasms.

If it is said that knowledge of sensible things is not present in the separate substances: against this. For they will at least have some higher kind of knowledge. And, since it is necessary that they not be absent from the possible intellect, if the possible intellect understands the separate substances, it will possess a twofold science: one by way of the separate substances; another received from the senses. And thus one of the two would be superfluous.

2. Concerning this argument, doubt is raised in two ways. First, because the first inference does not seem to be true. For the species existing in the intellect of one separate substance are not causative of species in the intellect of another separate substance. Nor does one separate substance understand through the species of another separate substance: since the intellect of the one understanding must be informed by an intelligible species. Therefore, although the species of sensible things exist intelligibly in a separate substance, it does not follow that the intellect understanding separate substances receives from them knowledge of sensible things.

Second, because it does not seem that, if the intellect has that twofold knowledge, one of them is superfluous. For if the intellect has some knowledge of God and some of sensible things, neither is superfluous; otherwise either Metaphysics or Natural Philosophy would be superfluous. In the same way, if the possible intellect has one science in the manner of the separate substances, which would be higher than the cognition of sensible things, and another received from the senses, by which it knows those sensible things themselves: it is not necessary for one of them to be superfluous and useless.

3. To the first of these it is said that the argument proceeds from a supposition about the mode of understanding that Averroes himself seems to hold, in Book III of the De Anima, comment 20 and 36 ¹⁹; as Saint Thomas also attributes to him, Book IV, d. XLIX, q. II, a. 1. For he holds that the intellect which he calls material, considered in itself and not insofar as it is conjoined to us, always understands separate substances, on the ground that the separate substance itself is united to the material intellect, just as the substance of the agent intellect is united to it. For according to this position, just as we hold that the intellect of the Blessed always sees the divine essence because the divine essence is united to the intellect by way of an intelligible form, so it is held that the intellect understands separate substances because they are united to the intellect by way of an intelligible form. And therefore, just as those seeing the divine essence see all created things, as it were represented through that essence itself, in which they exist intelligibly, so the intellect seeing a separate substance essentially as it is in itself, if sensible things are contained intelligibly in the separate substance, sees sensible things in the very essence of the separate substance as represented through that essence, and thus in it acquires knowledge of sensible things; just as those seeing the divine essence acquire in it knowledge of the things that are represented to them through the divine essence. — If, moreover, it is held that the intellect understands separate substances not because they are united to the intellect, but through species, the proposed conclusion still follows. For however the intellect may know them, if it knows them quidditatively and perfectly, it will see the species existing in them by which sensible things are represented, as their properties, or as having identity with the essence of the separate substance. And thus it will know sensible things in the separate substances. — From these things it is clear that Saint Thomas's inference is excellent: not because, given species existing in a separate substance, species must flow forth into the material intellect; but because through the species existing in the separate substance and known, it will understand material things.

But when it is objected against this, that one separate substance does not understand through the species of another separate substance, the reply is that indeed one intelligence does not understand through species existing in another intelligence as through an elicitive principle of its operation; but it can well understand through them as through a thing known in which other things are seen; just as we say the Blessed see creatures through the divine essence seen by them.

But if it is asked: What will be the elicitive principle of this kind of cognition by way of an intelligible species? — the answer is that to what is seen in another we need not assign its own proper and adequate species as the principle of its cognition, but the species of that in which it is seen suffices: for all things seen in a mirror are seen through the species of the mirror, and all things known in the divine essence are seen through the divine essence united to the intellect. So too we shall say that through the form by which the material, or possible, intellect sees the separate substance—whether it be the separate substance itself or its species—it will also see the sensible things that are represented in it.

4. To the second it is said that, when the response brought forward by Saint Thomas denies that separate substances have cognition of sensible things, it does not intend to deny that separate substances have cognition of sensible things on the side of the thing known—as if they in no way know sensible things, as the objection supposes—but on the side of the intelligible medium: just as in the argument it had been assumed that in separate substances there are species of sensible things intelligibly, namely because such a substance does not understand through species proportioned and adequate to those sensible things themselves, but through higher and more universal ones. And this Saint Thomas calls a higher cognition. And thus it follows that the other cognition of sensible things would be superfluous. For if the intellect knows sensible things through the inspection of higher and more universal species existing in a separate substance, there will be no need for it to receive cognition from sensible things, since that is a sufficient cognition of sensible things. And thus the cognition received from sensible things will be superfluous.

If it were said that none of these cognitions would be superfluous, because they are cognitions of different formal aspects, just as in Christ there is both infused and acquired knowledge: this does not stand. For although they would be of different formal aspects in some way, each would nevertheless be natural. And therefore, if the intellect naturally knows sensible things in the manner of separate substances, another natural cognition of those same things will be superfluous to it: for one cognitive power is satisfied by one natural knowledge with respect to the same things. It is not, however, similar with infused and acquired knowledge in Christ: because the infused knowledge in Christ was not natural to Christ's soul united to a body. For it is not unfitting that the intellect, even with respect to those same things that it knows naturally, be perfected by God in a higher manner.

XIV. Fifteenth. It would follow that we would understand separate substances: for the possible intellect is that by which the soul understands. This is false, as is clear from book II of the Metaphysics ²⁰. Therefore, and so on.

If it is said, following Averroes, that the possible intellect understands separate substances insofar as it is subsisting in itself, and is in potency to them as the diaphanous is to light; but that it is in potency to forms abstracted from phantasms insofar as it is conjoined to us, from the beginning; and therefore we do not understand separate substances through it from the beginning — an objection is raised against this.

Then, because it is prior to consider the intellect as in potency to such species than as it is joined to us—since it is posited as joined to us through such species—therefore it is not by being joined to us that it is in potency to such species.

Then, because being in potency to such species would not belong to it per se but through another—namely, through its continuity with us. And thus the possible intellect would not be fittingly defined by the fact that it is in potency to such species, as it is defined in III De Anima; for nothing is defined by those things that do not belong to it in itself.

Then, because if the intellect understands separate substances and species abstracted from phantasms, it must be that either it understands separate substances through such species, or conversely, through those very separate substances it understands such species; since it is impossible for the possible intellect to understand many things at once (namely, in perfect act) unless it understands one thing through another, given that one power is not perfected at once by several acts unless they have a natural order among themselves, that is, unless they have between them a natural order and concomitance. Whichever of these is granted, we must understand separate substances. For if we understand sensible things insofar as the intellect understands them—and the intellect understands them by this, that it understands separate substances—then we too must likewise understand them. And similarly if it be the converse:

namely, that the intellect understands separate substances by the very fact that it understands sensible things.

2. It must be noted that St. Thomas seems in this place to posit the intelligible species as that which is known, although elsewhere ²¹ he posits them as that by which the intellect knows. We can interpret his mind on this point in two ways. First, that although the species abstracted from the phantasms are not what is understood first and directly, but stand rather as the principle by which understanding occurs, nevertheless they are understood secondarily and indirectly. And thus the argument proceeds concerning them.

Second, that by species abstracted from phantasms he wishes to understand the universal natures of sensible things, which, insofar as they are universal, are abstracted from phantasms and from singulars. For since separate substances and sensible things are formally distinct intelligibles, and do not agree in one formal ratio of object, much less can they be understood simultaneously by the possible intellect than two sensible things can, unless one of them is understood through the other.

But how the possible intellect cannot understand many things at once was shown above ²².