The essays collected in this volume and written between 1959-1980 clearly belong to professional philosophy in both tone and context. Yet their ultimate aim is to explore larger problems and to set the groundwork for dealing with them. For the focus of attention throughout is human nature, not so much in the details of its structure or its social and moral manifestations as in its most general features and constituents. What sort of beings we are and how mind and body are related is the question at the very core of all inquiries into human nature.