The New Yorker reviews Peter Beinart's new book on American foreign policy and finds a tale of American leaders coping with the effects of unprecedented mistakes following the rise of the U.S. "Since American life in the twentieth century was a nearly unbroken ascent to greater wealth and power, American leaders had to keep relearning the lesson of limits. Wilson and the Progressives came to power during a long and prosperous peace, passed legislation that brought a moral order to the brute forces of industrialism and machine politics, believed that international relations could be similarly rationalized, plunged into the European inferno of the First World War, and saw their dream of a League of Nations crushed by the more hardheaded Georges Clemenceau, in Paris, and Senator Henry Cabot Lodge, in Washington."