Summary: On the Soul (page 4)

Book III

Aristotle rejects the idea of a sixth sense beyond those he has just listed (sight, hearing, smell, taste, and touch).

Intelligence is distinct from sensation; otherwise, there would be no errors. The former belongs to only a few animals, while the latter is common to all.

Imagination is the faculty by virtue of which we say that an image arises within us ¹.

It cannot exist without sensation. However, they are distinct faculties, since sensations are always true, whereas images are, most of the time, false ². Moreover, images arise even with the eyes closed.

Imagination often deceives us:

By virtue of the persistence of images and their resemblance to sensations, animals perform many actions under their influence: some, because they lack intelligence — these are the beasts — others, because their intelligence is sometimes clouded by passion, illness, or sleep — as is the case with humans ³.

Aristotle now examines the intellect. This is that by which the soul thinks and conceives ⁴.

Just as sensation is acted upon by the sensible, so the intellect suffers from the action of the intelligible ⁵. Alternatively: The intellect relates to intelligibles in the same way that the sensory faculty relates to sensibles ⁶.

When one understands something, the intellect becomes what it understands. One becomes knowledgeable when the intellect has become each of the intelligibles ⁷.

Therefore, thinking all things, the intellect must be without mixture ⁸. This receptacle — the intellect — must be entirely without form in order to receive intelligible forms perfectly.

Just like sensation, the intellect has no other proper nature than that of being in potency and it is in act no reality before thinking ⁹.

It is therefore in no way mixed with the body; otherwise, it would have a determinate quality — such as cold or heat — and would already be in act.

Thus, the sensible faculty does not exist independently of the body, while the intellect is separate from it ¹⁰.

Aristotle distinguishes between patient intellect and agent intellect.

The patient intellect is the one just described — that which becomes all intelligibles through the act of intellection.

The agent intellect is the efficient cause of these intelligibles. It is in act, separate from the body, impassible and unmixed — being by its very essence an act. The agent intellect surpasses the patient intellect, for always the agent is of a dignity superior to the patient ¹¹. It always thinks.

The dianoetic faculty has as its object not pleasure or suffering, but good and evil. Aristotle examines the nature of the practical intellect, which, unlike the theoretical intellect, does not contemplate separate things.

He recalls the principle that the soul is in a sense the very beings because science is in a sense identical with its object, like sensation, identical with the sensible ¹². Aristotle thus continues to lend some credence to the idea that only like can know like.

He makes an analogy with the hand:

The soul is analogous to the hand: just as the hand is the instrument of instruments, so the intellect is form of forms and the sense, form of sensibles ¹³.

Man is moved by the desirable.

Here we find articulated the famous principle that nature does nothing in vain ¹⁴. Indeed, all natural things exist for the sake of an end ¹⁵.

¹ II, 1, 412a
² ibid.
³ ibid.
⁴ ibid., 412b
⁵ II,2, 414a
⁶ II, 3, 415a
⁷ II, 4, 416a
⁸ II, 9, 421a
⁹ II, 11, 424a