In De Anima II.6, Aristotle divides perceptibles into three kinds: “special” perceptibles such as colors, sounds, and flavors, which can be perceived in their own right by only one sense; “common” perceptibles such as shapes, sizes, and movements, which can be perceived in their own right by multiple senses; and “incidental” perceptibles, such as the son of Diares, which can be perceived only “incidentally.” In this chapter, I explain what this division amounts to. First, I argue Aristotle’s distinction between perceiving something in its own right and perceiving it incidentally marks a causal distinction: what is perceived in its own right causes perception as such, while what is perceived incidentally coincides with what is perceived in its own right. Second, I argue that, for Aristotle, special perceptibles, unlike common ones, belong to homogeneous bodies on account of their chemical composition and affect sense organs along a range between contrary extremes. Finally, I explain the primacy Aristotle assigns to special perceptibles and his claim that perception of them alone is free from error. I conclude with some brief reflections on the primary/secondary quality distinction.