In the middle of the twentieth century, having outgrown a theological liberalism, Niebuhr challenged and rethought the nonsocialist Left in American politics. He developed a political realism that refused to sacrifice ideals to mere pragmatism, or politics to bitterness and greed. He examined the problem of morality in an immoral society and reimagined the balance between rights and freedom for the individual and social justice for the many. With brevity and deep insight, Lemert shows how Niebuhr's ideas illuminate our most difficult questions today.