Commentaria in Summam contra Gentiles, Liber II

Because someone could reply to the preceding arguments on the basis of Avicenna's position, Saint Thomas disputes Avicenna's position itself in this chapter ¹. In regard to this he does three things: first, he sets out that position together with its foundations; second, he refutes it ²; third, he replies to its foundations ³.

I. As to the first point, Avicenna says first, in his book On the Soul, that in the intellect the intelligible species do not remain in act except as long as they are being understood. He proves this by the following argument. As long as the apprehended forms remain in an apprehensive power, they are actually apprehended. Therefore, when they are not apprehended, they do not remain in it. The antecedent is proved: because from the fact that they are actually apprehended, sense in act becomes the sensed thing in act, and the intellect in act is the thing understood in act.

He says second, that the powers which preserve forms not apprehended in act differ from the intellect in two ways. For these are not apprehensive, but treasuries of the apprehensive powers: just as imagination is a treasury of forms apprehended through sense; and memory, according to him, is a treasury of forms apprehended without sense, as when a sheep apprehends the enmity of the wolf. Likewise, they have bodily organs in which forms are received by a reception close to apprehension: and thus the apprehensive power apprehends in act when it turns itself toward treasuries of this kind. — The intellect, however, is an apprehensive power; and it has no bodily organ.

He says third, that whenever we understand in act, intelligible species flow into our possible intellect from the agent intellect, which he posits as a certain separate substance. He shows this because we cannot say that the species by which we understand in act are preserved in a bodily organ, or in a power having an organ: for such forms are only potentially intelligible. Nor yet that they subsist per se, to which our intellect would be related as a mirror is to the things seen in a mirror: for this is Plato's opinion, rejected by Aristotle. It remains, therefore, that they flow into the intellect from some separate agent.

He says fourth, that there is a difference between man when he first learns and when he afterwards wishes to consider what he previously learned: because, since learning is nothing other than acquiring a perfect habit of joining himself to the agent intellect so as to receive from it an intelligible form, before learning man is in mere potency for such a reception of form; but after learning, he is like a potency disposed and adapted.

This opinion can be confirmed, because Aristotle, in the book On Memory and Recollection, shows that memory is not in the intellectual part but in the sensitive part; and thus it seems that preserving intelligible species does not pertain to the intellectual part.

2. With regard to this opinion of Avicenna, it must be noted, from what he says in the Fifth Part of the Sextus Naturalium ⁴, that the relation of the intelligence giving intelligible forms to our souls is like the relation of the sun to our eyes. And therefore, just as by the light of the sun that which was previously not seen is seen in act, so the intelligence draws our souls from potency into act through an illumination made upon the intelligibles, so that we understand in act what we did not previously understand in act. And just as our eyes do not see except at the presence of the sun, from which light flows forth, or at the presence of some other luminous body taking its place; so we do not understand in act except while intelligible species flow forth from the intelligence into the possible intellect. But a form does not flow forth from the intelligence into the possible intellect unless there be within us a potency prepared for its reception, by which preparation it becomes apt for conjunction with the agent intelligence. And because this comes about through the act of learning, therefore he says that after learning there is in man a potency adapted to the reception of an intelligible form.

II. As to the second ⁵, it is argued against this position in several ways.

First. Because from this opinion, just as from Plato's opinion, it follows that our knowledge is not caused by sensible things. That this is false appears from this sign: one who lacks a certain sense lacks knowledge of the sensibles that are known through that sense. Therefore, and so on.

If it is said that the intellect depends in some way on sensible things: because the possible intellect, by gazing upon the singulars present in the imagination, is illuminated by the light of the agent intellect so as to know the universal; and because the actions of the imagination, memory, and cogitation dispose the soul to receive the emanation from the intelligence — this is something new, and it does not seem probable. For we see that our soul is disposed to receive from separate substances all the more, the more it is removed from sensible and corporeal things; for by withdrawing from what is below, one draws near to what is above.

From this corollary it follows that Plato pursued the root of his position more successfully, for he held sensible things to be only what arouse the intellect to the consideration of those things whose knowledge it had from an external cause, and not what dispose the soul to receive the influx of separate forms. For since separate substances are immobile and always in the same condition, knowledge of things, according to him, always shines forth from them into our soul.

2. Note that we must speak one way about our soul if we hold that, through the power of the agent intellect existing within it, it receives knowledge from sensible things; and another way if we say that it receives knowledge from a separate intelligence through the illumination of the intellect, as Plato wished and Avicenna. For since our soul is midway between the separate intelligences and sensible things—existing above the order of sensibles insofar as it is not comprehended by matter, as was shown above ⁶, and existing below the order of intelligences insofar as it is the form of a body, though it approaches that order insofar as it is immaterial—the more it draws near to one of those extremes, the more it must recede from the other. And therefore, by approaching sensible things, turning itself toward them in its operation, it is drawn further away from the intelligence, so as to be less apt to receive its influx. Hence Saint Thomas rightly says that it is not likely that, by the intellect's gazing upon singulars present in the imagination, it should be illuminated by a separate intelligence for knowledge of the universal; for we see the opposite in our own soul: the soul is not drawn to participation in the higher order except by its withdrawal from the lower order.

But if we suppose that the soul receives knowledge from sensible things through the power of the agent intellect, then in the reception of knowledge the soul is not drawn toward participation in a higher order: since the agent intellect is of the same order as the possible intellect, inasmuch as each is an immaterial power rooted in the essence of the soul alone; and the agent intellect is related to the possible intellect as a proper agent to a proper patient, which in acting upon the possible intellect uses it as an instrument in the service of the phantasm, drawing forth from its active power the intelligible species. Therefore, by the fact that the soul apprehends singular things and considers them in phantasms, it is neither impeded nor held back from the reception of knowledge, but rather is helped: inasmuch as it places sensible things in such a mode of being that they are apt to receive the illumination of the agent intellect, and with it to impress the intelligible species upon the possible intellect. And by this mode of receiving knowledge, which Aristotle posited, the necessity of the union of our soul with the body is preserved. This cannot be preserved according to the position of Plato and Avicenna, as Saint Thomas shows in the Prima, q. 84, a. 4.

III. Second, an argument is brought against the aforementioned position. The esse of the possible intellect is firmer than the esse of corporeal matter. Therefore, since the forms flowing into corporeal matter are preserved in it by an intelligence, they are preserved all the more in the possible intellect. — The consequence is evident, because what is received into something is in it according to the mode of the receiver.

Note that the esse of the possible intellect is said to be firmer than the esse of matter, not because matter is corrupted while the possible intellect is not, since both of these are incorruptible; but because matter, according to its essence and nature, is a principle of variation and transmutation, whereas the intellect is not.

It must also be noted that Avicenna, just as he posited a separate intelligence causing knowledge in our souls, through acts of the sensitive powers by which they are disposed and prepared, so also posited that from the intelligence, which he calls the giver of forms, as is said in Potentia, q. VI, a. 3, substantial forms are caused in matter by natural agents, the matter being disposed for the reception of the forms. And therefore in this argument Saint Thomas takes from Avicenna's very position that the forms flowing from the intelligence into corporeal matter are preserved in it, namely even if they are not actually operating.

IV. Third. In sensitive cognition there is something that preserves what has been apprehended. Therefore much more so in intellective cognition, since it is more perfect.

It must be noted that, fittingly from the greater perfection of intellective cognition over sensitive cognition, Saint Thomas argues in the intellective part that the species is conserved. For a more noble cognition argues a greater nobility of the power. And therefore, if intellective cognition is more noble than sensitive cognition, it follows that the intellective power is more noble than the sensitive. Since, then, it pertains to the nobility and perfection of a power that it have in act the form by which it can operate, if this is attributed to the sensitive power—while something conserving the apprehended is posited in it—much more must this be attributed to the intellective part.

Fourth. Things that are diverse in the lower order of powers belong to diverse powers, but in the higher order they belong to one power: as is evident in the case of the common sense with respect to the things sensed. But to apprehend and to preserve in the sensitive part belongs to diverse powers. Therefore in the intellective part they are united.

Note that this argument destroys the foundation of Avicenna's position. For he himself, as is clear from what was said above ⁷, held that one sensitive power is apprehensive and another is retentive, insofar as it exists in a bodily organ; and therefore, because the intellect is an apprehensive power and has no corporeal organ, it does not belong to it to retain. But by this argument it is shown that, although in the sensitive part one power is posited as apprehensive and another as retentive, in the intellect there must nevertheless be one and the same power to which both belong. And thus that foundation of Avicenna's is of no account.

Fifth: and it is against the fourth statement of Avicenna. If learning were nothing other than a man's being made fit so as to be united with the agent intelligence, then one who learns one science would not learn it any more than another: because, according to him, the agent intelligence infuses all sciences. But this is known to be false. Therefore, etc.

Finally, it is argued that this opinion is contrary to the mind of Aristotle, who, in III De Anima, says that the intellect is the place of species—which is nothing else to say than that it is the treasury of them, to use Avicenna's words. — Likewise, that when the possible intellect acquires knowledge, it is able to operate by itself, even though it does not actually understand. — Likewise, in VIII Physics, text 32, that before learning, man needs a mover by whom he is reduced to act, but not afterward. — And thus, according to Aristotle, the species remain in the intellect, given that it does not understand actually.

That they are also not in the intellect from a separate substance, according to Aristotle, is clear because in III De Anima, text 39, he says that phantasms are related to the possible intellect as sensible things are to the sense. But it is evident that sensible things cause species in the sense. Therefore phantasms must also cause species in the intellect, and not a separate intelligence.

V. As to the third point, a reply is given to the two arguments brought forward in favor of Avicenna's opinion ⁸. To the first, when it was argued that as long as the apprehended forms remain in the apprehensive power they are actually apprehended: the reply is that this is false. For sometimes they are in perfect act in the intellect—and this is when the intellect actually considers them; but sometimes they are in imperfect act, namely in an intermediate way between potency and act—and this is when the intellect does not actually consider them.

This response is confirmed by the words of Aristotle, in De Anima III, text 8, where he states that an intellect possessing knowledge is indeed knowing in act, and can operate by itself, yet is nevertheless in some way in potency, though not as before learning or discovering.

It must be noted that, because Avicenna saw that in Aristotle's view species must not be posited in sense and intellect on any other ground than that sense in act be the thing sensed in act, and intellect in act the thing understood in act, through the very species; and because he thought that a thing is said to be "sensed in act" when it is actually sensed, and "understood" to be in act when it is actually understood: he therefore concluded that sense in act is the very thing sensed when the thing sensed is actually sensed, and likewise that intellect is one with the thing understood when it is actually considered. And since a thing is not sensed except by an act of sense, nor understood except by an act of intellect, it followed that intellect is not in act through an intelligible species unless it actually understands by means of it, nor sense through a sensible species unless by means of it it actually senses and cognizes the sensible. And thus, when the act of cognition ceases—since, according to him, the apprehensive power would then cease to be one with the thing apprehended—the intelligible species would cease to inform the intellect. But from the reply which Saint Thomas here gives, on Aristotle's mind, it appears that Avicenna was deceived because he did not know how to distinguish between esse in actuality perfected and esse in actuality imperfect and habitual. For the thing sensed and the thing understood, when actually perceived, are in perfected actuality, and are perfectly one, as regards cognizable esse, with sense in act and intellect in act, which then are themselves also in perfected actuality. When, however, they are not actually perceived but have their species in sense and intellect, they are then in imperfect cognizable actuality, just as sense and intellect are in imperfect actuality. And thus they are one imperfectly with sense in act and intellect in act.

2. To the second, when the authority of Aristotle was adduced, saying that memory is not in the intellective part, it is answered by denying the consequence. For although memory, which is only of the past as past, and consequently does not abstract from particular conditions, is only in the sensitive part and not in the intellective, which is of universals, it does not follow that the intellect is excluded from being conservative of intelligible species, which abstract from all particular conditions.

It must be noted, according to the doctrine of Saint Thomas in the First Part, q. 79, a. 6, that memory can be taken in two ways. In one way, for the power that merely conserves the species. And thus it is found in the intellectual part; and it is not really distinct from intellect, but the intellect itself, insofar as it conserves intellectual species, is called memory. In another way, as it is of the past insofar as it is past: and thus it is not in the intellectual part — understand, as is said in the First Part there, ad 2: if pastness holds per se on the side of the object, but not if it holds on the side of the operation; for thus the ratio of memory is preserved even in the intellectual part, inasmuch as it understands itself to have understood previously — but it is only in the sensitive part, which apprehends particulars. — And this distinction Saint Thomas here places implicitly in his reply.

VI. But one difficulty arises. For in the separated soul there are only the powers of the intellective part. And yet the separated soul knows the past as past; otherwise, as is said in Qu. de Anima, art. 20, it would not remember what it did in life, and thus the worm of conscience would perish. Therefore we must posit in the intellective part a memory which is of the past as past.

VII. To make the difficulty of this evident, it must be considered that, since "the past," as past, signifies esse under a determinate time, it says something under a particular condition. And therefore the judgment concerning the soul is the same with respect to knowledge of the past as past and with respect to knowledge of particulars. Now since there are two kinds of singulars, namely the material singular and the immaterial singular, the immaterial singular is not excluded from intellectual cognition, but only the material singular: as Saint Thomas says in the First Part, in the place cited above ⁹, ad 2. Therefore, according to the mode in which the soul is related to the material singular while joined to the body or separated from it, it must be investigated whether there is or is not memory in the intellective part.

It must therefore be known, according to the doctrine of St. Thomas ¹⁰, that the soul united to the body, because it understands through species abstracted from particular material things—species which represent only the universal nature abstracted from material conditions—cannot directly understand the singular; rather, it understands singulars only reflexively, when it reflects upon its own operation and upon the principle of that operation, and upon the phantasm from which the intelligible species is caused. Yet this reflection cannot be accomplished without the aid of the cogitative and imaginative powers, which are sensitive powers. Directly, however, it knows those same singulars through the sensitive powers, insofar as a similitude representative of the nature is received in sense with respect to its individual conditions. But the soul separated from the body, besides the forms which it acquired while united to the body, also has species infused into it by the divine light, similar to the species found in angelic minds, which are representative not only of the universal nature but also of singulars and of particular conditions; and these species represent to the soul only those singulars of which it has some determinate relation, as is said in the First Part, q. LXXXIX, a. 4—whether by prior cognition, or by some affection, or by a natural relation, or by divine ordination. For all these things render the soul in some way disposed toward an intelligible form, so that it represents to itself these or those singulars. And therefore by means of those species the separated soul can know not only universals directly, but particulars as well.

From which it follows that in the conjoined soul, as regards the intellective part, there is no memory by which the past is known as past: because the species in the intellect does not represent particular conditions, but only a universal nature. But there is indeed such memory as regards the sensitive part: because in it is received a species representative of an individual thing under a determinate place and determinate time. – In the separated soul, however, there is indeed a receptive power for a species representative of individuals under a determinate past time, because species of this influxed kind represent individuals under particular conditions; yet nevertheless the intellect itself, in which are species of this kind representative of previously known individuals, does not properly have the character of memory, according to what the philosophers have said about memory; because it does not have those species by which in this life they were known under some temporal difference, since those were never in the intellect, but only in the potentiality of the sensitive part, as has been shown; but memory properly taken is a conserving power of the species by which things have been previously known, and is cognitive of the past as past through species received from sensibles, by which that thing was known. – If, however, memory be taken as cognitive of the past under the aspect of past through influxed species, and not through species received from sensibles; thus the intellect of the separated soul, not of the conjoined soul, which does not have species of this kind, is memory: for by them it knows those things which it had formerly known, while conjoined, through the sensitive powers. And perhaps, after it has actually known those things, or even other individuals, it can cease to know them actually, and remain in habitual potency to knowing them.

2. It is therefore evident, first, that with respect to the power that is called memory, distinct from a power merely receptive of species and not conserving them, there is no memory in the intellective part, but only in the sensitive part. For, as was shown above ¹¹ in the intellective part the same power is both receptive and conservative of species, although in the sensitive part they are distinguished.

It is clear, secondly, that with respect to this property, namely retaining and preserving species, memory is found in the intellective part, both in the soul as joined to the body and in the soul separated from it: since it was shown above ¹² that intelligible species are preserved in the intellect.

It is evident, third, that, with respect to the property of memory which is to know the past absolutely under the aspect of the past by means of a species existing in the memorative power itself and directly representing the thing under past time, an intellectual memory is found, not indeed in the soul joined to a body, but in the separate soul: because the species that are in the intellect joined to a body are acquired by way of the senses, and are not representative of particular conditions; but the species infused into the separate soul are so.

It is clear, fourth, that, with respect to that property of memory in which the proper account of memory among the philosophers consists—namely, to preserve the species received from sensible things by which the past was cognized under past time—it is not found in the intellective part, neither conjoined nor separate.

3. Hence, in reply to the objection made at the beginning, the consequence is denied concerning memory properly so called, which is found in the soul insofar as it is cognitive through species acquired from the senses. For it does not suffice for the account of memory properly so called that the past be known under the aspect of the past, nor does Saint Thomas intend this; rather what is required is that it be known through the same species received from the senses by which it was previously known. – But if it is understood of memory insofar as, through infused species, the soul knows what it knew in life through the senses, then it is granted that there is memory in the separated soul with respect to the past. Nor does Saint Thomas wish to deny this; he denies it only of the intellective power insofar as it understands through intelligible species taken from sensible things; for by these the soul, whether joined to the body or separated, does not know the past under the aspect of the past, since they abstract from every difference of time, and being past accrues to the nature represented by the intelligible species abstracted from sensible things, in this way.