These celebrated lectures, delivered at the University of Chicago in 1950, were for many years the most widely read account of American diplomacy in the first half of the twentieth century. They were written against the backdrop of the searing experience of total war, and Kennan's strictures against the "legalistic- moralistic" tradition in U.S. foreign policy need to be understood in that light. It was not that Kennan was hostile to law or morality as restraints upon our own conduct; at the root of his opposition to the crusading impulse was the fear that it would subtly erode, if not smash, the barriers to a yet more terrible war. The second edition of this work contains two lectures from 1984 that reconsider the themes of American Diplomacy and bemoan "the extreme militarization not only of our thought but of our lives that has become the mark of this postwar age." Kennan's worst fears did not come to pass, and it may be that he fell victim to exaggerations comparable to those he deplored in American policymakers. But we have needed his voice to remind us that "there are problems in this world that we will not be able to solve, depths into which it will not be useful or effective for us to plunge, dilemmas in other regions of the globe that will have to find their solution without our involvement."