Aristotle rejected the notion that a fiery ray emanated from the eye and reflected back from the objects to create sight—on the grounds that if this were so, night vision would be normal. By the same token he objected to the theory of emanations from objects, since the eye does not perceive them when the objects are pressed against the closed eye. He postulated the necessity of a medium between the eye and its percept, and reached back to the Presocratic translucence (diaphanes), which exists in water, air and translucent objects. Light is the agent (energeia) that reveals translucence as an incorporeal state ranging from bright to dark. Insofar as this flows into objects it ceases being mere light and reveals color as well as their substantiality. The color of the object in turn puts the medium itself in motion and this is transmitted to the eye. Obviously, the role of light is to make this process possible, but Aristotle attributes no movement to it, whereas the resulting color is an activator (kinetikon) of the medium (Benson, 2000). Aristotle’s theory of color contrasts thus with Empedocles and Plato, in the sense that “the assimilation of the sensible form without the matter of the perceived object” is how Aristotle defines perception: “color is a power to move, or alter, what is transparent”. He draws a clear distinction between the physiological activity in the eye and the sensory presentation of color to the perceptive part of the soul. Aristotle conceives of light as incorporeal activity. It is a state of a potentially transparent medium, a state akin to, or equivalent to, a state of illumination.
For Aristotle, a substance together with its accidents forms a certain whole. The whole would seem to be such that substance is the first part, after which come quality, quantity, and the other accidents (Metaph. XII, in init.) (Brentano, 1981, p. 82). Aristotle is convinced that whole and part can never be actual simultaneously. At the root of his theory of categories is a theory of the relation of whole and part. If the whole is actual, then the part is merely potential. How does this applies to a thing extended in space? Conceptually, the accident always contains the substance, hence the real unity of the accident. Concept red contains, in Aristotle’s view, the concept colored, and the concept colored contains the concept sensibly qualitative. What is in question in Aristotle’s theory of categories is thus that it is not the plurality of individual parts; rather all attributes entering into the definition determine one and the same individual. Like any other scientific terms, “category” as undergone several changes of meaning in the course of history, Brentano himself disagreed in several arguments with Aristotle (see Brentano, 1981, part II pp. 81-89). Nevertheless, “this much is certain: he [Aristotle] thought that there was a sense of the term being for each category; and in making the classification, he wanted to distinguish as many different senses of being” (Brentano, 1981, p. 90). Thus, to arrive at the true understanding of perception, we must see the distinction between a subject and that which the subject underlies, such as sensible, quality, place, real time, extension, shape, – in fact, substantial determinations.
 For a detailed analysis, see Kalderon, M. E. (2015). Form without matter: Empedocles and Aristotle on color perception. OUP Oxford.
Aristotle, (1998). Metaphysics translated with an introduction by H. Lawson-Tancred. Penguin.
Benson, J. L. (2000). Greek color theory. Greek Color Theory and the Four Elements, 6. Art, Architecture & Art History at ScholarWorks@UMass Amherst.
Brentano, F. (1981). The Theory of Categories. Melbourne International Philosophy Series, Vol. 8. London: Martinus Nijhoff Publishers.