Summa Theologica, Part I · Aquinas Thomas
QUESTION 78
Now, we must observe that as to sensible forms there is no difference between man and other animals; for they are similarly immuted by the extrinsic sensible. But there is a difference as to the above intentions: for other animals perceive these intentions only by some natural instinct, while man perceives them by means of coalition of ideas. Therefore the power by which in other animals is called the natural estimative, in man is called the "cogitative," which by some sort of collation discovers these intentions. Wherefore it is also called the "particular reason," to which medical men assign a certain particular organ, namely, the middle part of the head: for it compares individual intentions, just as the intellectual reason compares universal intentions. As to the memorative power, man has not only memory, as other animals have in the sudden recollection of the past; but also "reminiscence" by syllogistically, as it were, seeking for a recollection of the past by the application of individual intentions. Avicenna, however, assigns between the estimative and the imaginative, a fifth power, which combines and divides imaginary forms: as when from the imaginary form of gold, and imaginary form of a mountain, we compose the one form of a golden mountain, which we have never seen. But this operation is not to be found in animals other than man, in whom the imaginative power suffices thereto. To man also does Averroes attribute this action in his book _De sensu et sensibilibus_ (viii). So there is no need to assign more than four interior powers of the sensitive part--namely, the common sense, the imagination, and the estimative and memorative powers.
Reply Obj. 1: The interior sense is called "common" not by predication, as if it were a genus; but as the common root and principle of the exterior senses. Reply Obj. 2: The proper sense judges of the proper sensible by discerning it from other things which come under the same sense; for instance, by discerning white from black or green. But neither sight nor taste can discern white from sweet: because what discerns between two things must know both. Wherefore the discerning judgment must be assigned to the common sense; to which, as to a common term, all apprehensions of the senses must be referred: and by which, again, all the intentions of the senses are perceived; as when someone sees that he sees. For this cannot be done by the proper sense, which only knows the form of the sensible by which it is immuted, in which immutation the action of sight is completed, and from immutation follows another in the common sense which perceives the act of vision. Reply Obj. 3: As one power arises from the soul by means of another, as we have seen above (Q. 77, A. 7), so also the soul is the subject of one power through another. In this way the imagination and the memory are called passions of the "first sensitive."
Ideas discussed in this chapter
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