A long history of inquiry about human nature and the self stretches from the ancient tradition of Socratic self-knowledge in the context of ethical life to contemporary discussions of brain function in cognitive science. It begins with a conflict among the ancients. On one view, which comes to be represented most clearly by Aristotle, the issue is settled in terms of a composite and very complex human nature. Who I am is closely tied to my embodied existence. The other view, found as early a...