What is ethics? Where does it come from? Can we really hope to find any rational way of deciding how we ought to live? If we can, what would it be like, and how are we going to know when we have found it? This book is not a conventional reader in moral philosophy. To capture the essentials of what we know about the origins and nature of ethics, Peter Singer has drawn on anthropology, history, observations of non-human animals, the theory of evolution, game theory, and works of fiction, in addition to moral philosophy. By choosing some of the finest pieces of writing, old and new, in and about ethics, he conveys the intellectual excitement of the search for answers to basic questions about how we ought to live.