Carl Becker was a historian of history as well as a historian of the United States, and his place in American history rests as much on his capacity to raise provocative questions about the nature of historical study as on the history he produced. He preferred to regard himself as a thinker about history and historians rather than as a historian. His forte, he once remarked, consisted "in having thought a good deal about the meaning of history rather than in having achieved erudition in it." The remark was not entirely an expression of false modesty; he seemed never quite sure of his own knowledge. His attitude led him to pursue courses of conduct that are somewhat baffling to later observers. In 1928, while in the midst of writing what was to become an extraordinarily successful high school textbook, Modern History, Becker declined an invitation to speak at an...