Hans Morgenthau

Hans Joachim Morgenthau (February 17, 1904 – July 19, 1980) was one of the major twentieth-century figures in the study of international relations. Morgenthau's works belong to the tradition of realism in international relations theory, and he is usually considered among the most influential realists of the post-World War II period. Morgenthau made landmark contributions to international relations theory and the study of international law. His Politics Among Nations, first published in 1948, went through five editions during his lifetime and was widely adopted as a textbook in U.S. universities. While Morgenthau emphasized the centrality of power and "the national interest," the subtitle of Politics Among Nations —"the struggle for power and peace"— indicates his concern not only with the struggle for power but the ways in which it is limited by ethics, norms, and law.

Source: Hans Morgenthau on Wikipedia.