A leading historian of international affairs and a distinguished political scientist bring the rich experience of the past to bear upon the perplexities that confront today's statesman. They survey the evolution of the international system from the emergence of the modern state in the seventeenth century to the present, paying particular attention to the nineteenth century's balance-of-power system, principles of which still determine many of the usages of modern diplomacy. The author show, however, that this classical system has been profoundly altered by a twentieth-century diplomatic revolution: a complex of political, economic, military, and ideological factors that has destroyed the homogeneity of the international community and confronted diplomats with new problems and the need to find new expedients to deal with them. The effects of this revolution on the abortive experiment in system-making between the two world wars are described in detail, and the authors show how the modalities of the Cold War and the principles of the Nixon-Kissinger détente strategy were attempts to overcome them. The revised Second Edition includes an entirely new chapter on U.S.-Soviet cooperation and expanded coverage of the Reagan years, as well as a new analysis of the current international system.