  Here, at least, Aristotle points out what is obvious, that when a thinker’s soul is made like its cognitive object, it does not become one with some hylomorphic compound, but with its form: “for it is not the stone which is in the soul, but its form” (De Anima iii 8, 431b29–432a1; cf. iii 4, 429a27). The suggestion is, then, that when S comes to think of a stone, as opposed to merely perceiving some particular stone, S has a faculty which is such that it can become one in form with that stone. Aristotle sometimes infers from this sort of consideration that thought is of universals, whereas perception is of particulars (De Anima ii 5, 417b23, Posterior Analytics i 31, 87b37–88a7), though he elsewhere will allow that we also have knowledge of individuals (De Anima ii 5, 417a29; Metaphysics xiii 10, 1087a20). These passages are not contradictory, since Aristotle may simply be emphasizing that thought tends to proceed at a higher level of generality than perception, because of its trading in comparatively abstract structural features of its objects. A person can think of what it is to be a stone, but cannot, in any direct and literal sense of the term, perceive this.