Summa Theologica, Part I (Prima Pars) From the Complete...

I answer that, Since it is of the nature of the memory to preserve the species of those things which are not actually apprehended, we must first of all consider whether the intelligible species can thus be preserved in the intellect: because Avicenna held that this was impossible. For he admitted that this could happen in the sensitive part, as to some powers, inasmuch as they are acts of corporeal organs, in which certain species may be preserved apart from actual apprehension. But in the intellect, which has no corporeal organ, nothing but what is intelligible exists. Wherefore every thing of which the likeness exists in the intellect must be actually understood. Thus, therefore, according to him, as soon as we cease to understand something actually, the species of that thing ceases to be in our intellect, and if we wish to understand that thing anew, we must turn to the active intellect, which he held to be a separate substance, in order that the intelligible species may thence flow again into our passive intellect. And from the practice and habit of turning to the active intellect there is formed, according to him, a certain aptitude in the passive intellect for turning to the active intellect; which aptitude he calls the habit of knowledge. According, therefore, to this supposition, nothing is preserved in the intellectual part that is not actually understood: wherefore it would not be possible to admit memory in the intellectual part.

But this opinion is clearly opposed to the teaching of Aristotle. For he says (De Anima iii, 4) that, when the passive intellect "is identified with each thing as knowing it, it is said to be in act," and that "this happens when it can operate of itself. And, even then, it is in potentiality, but not in the same way as before learning and discovering." Now, the passive intellect is said to be each thing, inasmuch as it receives the intelligible species of each thing. To the fact, therefore, that it receives the species of intelligible things it owes its being able to operate when it wills, but not so that it be always operating: for even then is it in potentiality in a certain sense, though otherwise than before the act of understanding—namely, in the sense that whoever has habitual knowledge is in potentiality to actual consideration.

The foregoing opinion is also opposed to reason. For what is received into something is received according to the conditions of the recipient. But the intellect is of a more stable nature, and is more immovable than corporeal nature. If, therefore, corporeal matter holds the forms which it receives, not only while it actually does something through them, but also after ceasing to act through them, much more cogent reason is there for the intellect to receive the species unchangeably and lastingly, whether it receive them from things sensible, or derive them from some superior intellect. Thus, therefore, if we take memory only for the power of retaining species, we must say that it is in the intellectual part. But if in the notion of memory we include its object as something past, then the memory is not in the intellectual, but only in the sensitive part, which apprehends individual things. For past, as past, since it signifies being under a condition of fixed time, is something individual.

Reply Obj. 1: Memory, if considered as retentive of species, is not common to us and other animals. For species are not retained in the sensitive part of the soul only, but rather in the body and soul united: since the memorative power is the act of some organ. But the intellect in itself is retentive of species, without the association of any corporeal organ. Wherefore the Philosopher says (De Anima iii, 4) that "the soul is the seat of the species, not the whole soul, but the intellect."

Reply Obj. 2: The condition of past may be referred to two things—namely, to the object which is known, and to the act of knowledge. These two are found together in the sensitive part, which apprehends something from the fact of its being immuted by a present sensible: wherefore at the same time an animal remembers to have sensed before in the past, and to have sensed some past sensible thing. But as concerns the intellectual part, the past is accidental, and is not in itself a part of the object of the intellect. For the intellect understands man, as man: and to man, as man, it is accidental that he exist in the present, past, or future. But on the part of the act, the condition of past, even as such, may be understood to be in the intellect, as well as in the senses. Because our soul's act of understanding is an individual act, existing in this or that time, inasmuch as a man is said to understand now, or yesterday, or tomorrow. And this is not incompatible with the intellectual nature: for such an act of understanding, though something individual, is yet an immaterial act, as we have said above of the intellect (Q. 76, A. 1); and therefore, as the intellect understands itself, though it be itself an individual intellect, so also it understands its act of understanding, which is an individual act, in the past, present, or future.

In this way, then, the notion of memory, in as far as it regards past events, is preserved in the intellect, forasmuch as it understands that it previously understood: but not in the sense that it understands the past as something "here" and "now."

Reply Obj. 3: The intelligible species is sometimes in the intellect only in potentiality, and then the intellect is said to be in potentiality. Sometimes the intelligible species is in the intellect as regards the ultimate completion of the act, and then it understands in act. And sometimes the intelligible species is in a middle state, between potentiality and act: and then we have habitual knowledge. In this way the intellect retains the species, even when it does not understand in act. _______________________

Objection 1: It would seem that the intellectual memory is distinct from the intellect. For Augustine (De Trin. x, 11) assigns to the soul memory, understanding, and will. But it is clear that the memory is a distinct power from the will. Therefore it is also distinct from the intellect.

Obj. 2: Further, the reason of distinction among the powers in the sensitive part is the same as in the intellectual part. But memory in the sensitive part is distinct from sense, as we have said (Q. 78, A. 4). Therefore memory in the intellectual part is distinct from the intellect.

Obj. 3: Further, according to Augustine (De Trin. x, 11; xi, 7), memory, understanding, and will are equal to one another, and one flows from the other. But this could not be if memory and intellect were the same power. Therefore they are not the same power.

On the contrary, From its nature the memory is the treasury or storehouse of species. But the Philosopher (De Anima iii) attributes this to the intellect, as we have said (A. 6, ad 1). Therefore the memory is not another power from the intellect.

I answer that, As has been said above (Q. 77, A. 3), the powers of the soul are distinguished by the different formal aspects of their objects: since each power is defined in reference to that thing to which it is directed and which is its object. It has also been said above (Q. 59, A. 4) that if any power by its nature be directed to an object according to the common ratio of the object, that power will not be differentiated according to the individual differences of that object: just as the power of sight, which regards its object under the common ratio of color, is not differentiated by differences of black and white. Now, the intellect regards its object under the common ratio of being: since the passive intellect is that "in which all are in potentiality." Wherefore the passive intellect is not differentiated by any difference of being. Nevertheless there is a distinction between the power of the active intellect and of the passive intellect: because as regards the same object, the active power which makes the object to be in act must be distinct from the passive power, which is moved by the object existing in act. Thus the active power is compared to its object as a being in act is to a being in potentiality; whereas the passive power, on the contrary, is compared to its object as being in potentiality is to a being in act. Therefore there can be no other difference of powers in the intellect, but that of passive and active.

Reply Obj. 1: Although it is said (3 Sent. D, 1) that memory, intellect, and will are three powers, this is not in accordance with the meaning of Augustine, who says expressly (De Trin. xiv) that "if we take memory, intelligence, and will as always present in the soul, whether we actually attend to them or not, they seem to pertain to the memory only. And by intelligence I mean that by which we understand when actually thinking; and by will I mean that love or affection which unites the child and its parent." Wherefore it is clear that Augustine does not take the above three for three powers; but by memory he understands the soul's habit of retention; by intelligence, the act of the intellect; and by will, the act of the will.

Objection 1: It would seem that the reason is a distinct power from the intellect. For it is stated in De Spiritu et Anima that "when we wish to rise from lower things to higher, first the sense comes to our aid, then imagination, then reason, then the intellect." Therefore the reason is distinct from the intellect, as imagination is from sense.

Obj. 2: Further, Boethius says (De Consol. iv, 6), that intellect is compared to reason, as eternity to time. But it does not belong to the same power to be in eternity and to be in time. Therefore reason and intellect are not the same power.

Obj. 3: Further, man has intellect in common with the angels, and sense in common with the brutes. But reason, which is proper to man, whence he is called a rational animal, is a power distinct from sense. Therefore is it equally true to say that it is distinct from the intellect, which properly belongs to the angel: whence they are called intellectual.

On the contrary, Augustine says (Gen. ad lit. iii, 20) that "that in which man excels irrational animals is reason, or mind, or intelligence or whatever appropriate name we like to give it." Therefore, reason, intellect and mind are one power.

I answer that, Reason and intellect in man cannot be distinct powers. We shall understand this clearly if we consider their respective actions. For to understand is simply to apprehend intelligible truth: and to reason is to advance from one thing understood to another, so as to know an intelligible truth. And therefore angels, who according to their nature, possess perfect knowledge of intelligible truth, have no need to advance from one thing to another; but apprehend the truth simply and without mental discussion, as Dionysius says (Div. Nom. vii). But man arrives at the knowledge of intelligible truth by advancing from one thing to another; and therefore he is called rational. Reasoning, therefore, is compared to understanding, as movement is to rest, or acquisition to possession; of which one belongs to the perfect, the other to the imperfect. And since movement always proceeds from something immovable, and ends in something at rest; hence it is that human reasoning, by way of inquiry and discovery, advances from certain things simply understood—namely, the first principles; and, again, by way of judgment returns by analysis to first principles, in the light of which it examines what it has found. Now it is clear that rest and movement are not to be referred to different powers, but to one and the same, even in natural things: since by the same nature a thing is moved towards a certain place, and rests in that place. Much more, therefore, by the same power do we understand and reason: and so it is clear that in man reason and intellect are the same power.

Reply Obj. 3: Other animals are so much lower than man that they cannot attain to the knowledge of truth, which reason seeks. But man attains, although imperfectly, to the knowledge of intelligible truth, which angels know. Therefore in the angels the power of knowledge is not of a different genus from that which is in the human reason, but is compared to it as the perfect to the imperfect. _______________________

Objection 1: It would seem that the higher and lower reason are distinct powers. For Augustine says (De Trin. xii, 4,7), that the image of the Trinity is in the higher part of the reason, and not in the lower. But the parts of the soul are its powers. Therefore the higher and lower reason are two powers.

Obj. 3: Further, the Philosopher says (Ethic. vi, 1) that "the scientific part" of the soul, by which the soul knows necessary things, is another principle, and another part from the "opinionative" and "reasoning" part by which it knows contingent things. And he proves this from the principle that for those things which are "generically different, generically different parts of the soul are ordained." Now contingent and necessary are generically different, as corruptible and incorruptible. Since, therefore, necessary is the same as eternal, and temporal the same as contingent, it seems that what the Philosopher calls the "scientific" part must be the same as the higher reason, which, according to Augustine (De Trin. xii, 7) "is intent on the consideration and consultation of things eternal"; and that what the Philosopher calls the "reasoning" or "opinionative" part is the same as the lower reason, which, according to Augustine, "is intent on the disposal of temporal things." Therefore the higher reason is another power than the lower.

Obj. 4: Further, Damascene says (De Fide Orth. ii) that "opinion rises from the imagination: then the mind by judging of the truth or error of the opinion discovers the truth: whence mens (mind) is derived from metiendo (measuring). And therefore the intellect regards those things which are already subject to judgment and true decision." Therefore the opinionative power, which is the lower reason, is distinct from the mind and the intellect, by which we may understand the higher reason.

I answer that, The higher and lower reason, as they are understood by Augustine, can in no way be two powers of the soul. For he says that "the higher reason is that which is intent on the contemplation and consultation of things eternal": forasmuch as in contemplation it sees them in themselves, and in consultation it takes its rules of action from them. But he calls the lower reason that which "is intent on the disposal of temporal things." Now these two—namely, eternal and temporal—are related to our knowledge in this way, that one of them is the means of knowing the other. For by way of discovery, we come through knowledge of temporal things to that of things eternal, according to the words of the Apostle (Rom. 1:20), "The invisible things of God are clearly seen, being understood by the things that are made": while by way of judgment, from eternal things already known, we judge of temporal things, and according to laws of things eternal we dispose of temporal things.

But it may happen that the medium and what is attained thereby belong to different habits: as the first indemonstrable principles belong to the habit of the intellect; whereas the conclusions which we draw from them belong to the habit of science. And so it happens that from the principles of geometry we draw a conclusion in another science—for example, perspective. But the power of the reason is such that both medium and term belong to it. For the act of the reason is, as it were, a movement from one thing to another. But the same movable thing passes through the medium and reaches the end. Wherefore the higher and lower reasons are one and the same power. But according to Augustine they are distinguished by the functions of their actions, and according to their various habits: for wisdom is attributed to the higher reason, science to the lower.