This book explores one of the great questions of our time: How can we preserve our sense of what it means to be a person while at the same time accepting what science tells us to be true—namely, that human nature is continuous with the rest of nature? What, in other words, does it mean to be a person in a world of things? This book shows how the Jewish tradition provides rich ways of understanding human nature and personhood that preserve human dignity and distinction in a world of neuroscience, evolutionary biology, biotechnology, and pervasive scientism. These ancient resources can speak to Jewish, non-Jewish, and secular readers alike. Science may tell us what we are, the book says, but it cannot tell us who we are, how we should live, or why we matter. Traditional Jewish thought, in open-minded dialogue with contemporary scientific perspectives, can help us answer these questions. The book shows how, using sources ranging across the Jewish tradition, from the Hebrew Bible and the Talmud to more than a millennium of Jewish philosophy. Among the many subjects the book addresses are sexuality, birth and death, violence and evil, moral agency, and politics and economics. Throughout, the book demonstrates how Jewish tradition brings new perspectives to—and challenges many current assumptions about—these central aspects of human nature. A study of human nature in Jewish thought and an original contribution to Jewish philosophy, this is a book for anyone interested in what it means to be human in a scientific age.