Chapter 82 — That man needs sense powers in order to understand

However, we must realize that forms in bodily things are particular, and have a material existence. But in the intellect they are universal and immaterial. Our manner of understanding brings this out. That is, we apprehend things universally and immaterially. This way of understanding must conform to the intelligible species whereby we understand. Consequently, since it is impossible to pass from one extreme to another without traversing what lies between, forms reaching the intellect from bodily objects must pass through certain media.

These are the sense faculties, which receive the forms of material things without their matter; what lodges in the eye is the species of the stone, but not its matter. However, the forms of things received into the sense faculties are particular; for we know only particular objects with our sense faculties. Hence man must be endowed with senses as a prerequisite to understanding. A proof of this is the fact that if a man is lacking in one of the senses, he has no knowledge of sensible objects that are apprehended by that sense. Thus a person born blind can have no knowledge of colors.