Stephen Everson presents a comprehensive new study of Aristotle's account of perception and related mental capacities. Recent debate about Aristotle's theory of mind has focused on this account, which is Aristotle's most sustained and detailed attempt to describe and explain the behavior of living things. Everson places this account in the context of Arisotle's natural science as a whole, showing how Aristotle applies the explanatory tools he developed in other works to the study of perceptual cognition.