"The identity of intellect with the intelligibles may be demonstrated in this way. Anything it contemplates must either be held inside itself or be set in some other medium. The fact of its contemplation is clear, for with thought it comes to be, but the intellect bereft of thought is bereft of its very essence. A theory of contemplation must therefore be sought in the experiences that go with the various kinds of cognition.
"The cognitive faculties assembled inside us are perception, imagination and intellect. Whatever is attended to by means of perception is regarded externally: contemplation is not effected by union with its objects, but takes only an imprint from the encounter with them. No identity between the eye and the thing seen is therefore possible, for if it did not stand apart from its object it could not see. The object of touch would likewise cease to exist if it were brought into identity [with what senses it]. From these examples it is clear that perception and all activities involving perception must be outwardly applied, if any perceptible object is to be apprehended."
"The imagination tends outwardly in much the same way. The image generated through its operations is made to stand outside it, where by these same operations it is received as an externalized image. In this way are objects of sense and imagination apprehended: focused on themselves, these faculties would never hit on a single object, be it perceptible or imperceptible in form.
"The intellect's mode of apprehension is different, for its contemplation is focused and carried out on itself. As an 'eye' fixed on its own activities, if it were to go beyond contemplation of these it would intelligize nothing. Now the intellect's relationship to the intelligible is on the one hand analogous to that of sense and the sensible. But the latter contemplates its object outwardly, deriving the sensible from external matter. Intellect on the other hand concentrates on itself. Otherwise its direction would be outward -- as in the opinion of those who rejected the distinction between imagination and intellect as one of mere nomenclature. For they took intellect to be the imaginative faculty of a rational being. But if matter and the nature of bodies were (as in their view) the basis for all things, and it followed that intellect too depended on these, then whence would our contemplation derive its conceptions of beings, corporeal and otherwise? As abstractions, it is obvious that intellectual entities have no location in material space, and that intellection takes them up only insofar as they are intellectual, uniting them with the intellect and its intelligibles. In processing intelligibles the intellect observes itself; its operations take place through its approach to itself. And since the intelligibles are many -- for the intellect dwells on many things and not one -- it necessarily follows that intellect is a plurality. But prior to the many there is the One, and thus the One is necessarily prior to the intellect."
Sentence 43