Book excerpt: How ought we to live? What really exists? How do we know? This book introduces important themes in ethics, knowledge, and the self, via readings from Plato, Hume, Descartes, Hegel, Darwin, and Buddhist writers. It emphasizes throughout the point of doing philosophy, explains how different areas of philosophy are related, and explores the contexts in which philosophy was and is done. ABOUT THE SERIES: The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable.