Hans J. Morgenthau, a founding proponent of political realism, remains the central figure in international relations scholarship of the twentieth century. His book Politics among Nations literally defined the field in 1948 as it heralded the post--World War II paradigm shift in American thinking about diplomacy. Yet when Morgenthau died in 1980 at the age of seventy-six, no one present at his funeral had an inkling about the first half of his life...