Science once had an unshakable faith in its ability to bring the forces of nature—even human nature—under control. In this wide—ranging book Anson Rabinbach examines how developments in physics, biology, medicine, psychology, politics, and art employed the metaphor of the working body as a human motor.From nineteenth—century theories of thermodynamics and political economy to the twentieth—century ideals of Taylorism and Fordism, Rabinbach demonstrates how the utopian obsession with energy and fatigue shaped social thought across the ideological spectrum.