In recent years the majority of scholarship on Aristotle's philosophy of mind has concentrated on his account of sensation and has generally sought to find in his ancient account insights applicable to contemporary materialistic explanations of mental life. Challenging cognitivist and functionalist interpretations, this volume argues that Aristotle believed the mind to be unmixed, or separate from the body. Through careful textual analysis of De Anima and other key texts, the author shows that the Greek philosopher made a clear distinction between perception-an activity realized in material sense organs-and thinking-a process that cannot occur in any material organ. This innovative interpretation of Aristotle's theory of cognitive activities is a worthy contribution to an ongoing debate.