In a midcentury American cultural episode forgotten today, intellectuals of all schools shared a belief that human nature was under threat. The immediate result was a glut of dense, abstract books on the "nature of man." But the dawning "age of the crisis of man," as Mark Greif calls it, was far more than a historical curiosity. In this ambitious intellectual and literary history, Greif recovers this lost line of thought to show how it influenced society, politics, and culture before, during, and long after World War II.