The first biography of Hans Morgenthau, the theoretician who escaped Nazi Germany and pioneered the 'realist' approach to international relations, now resurgent in global politics.

'International politics, like all politics, is a struggle for power.' Hans Morgenthau wrote these words in 1948 as Americans were grappling with their emerging global rivalry with the Soviet Union. His Politics Among Nations quickly became the defining international relations textbook. Henry Kissinger stated, 'All of us who taught the subject after him, however much we differed from one another, had to start with his reflections.'

Morgenthau's realism was rooted in the traumas he experienced in interwar Germany. Amid the rampant anti-Semitism of this period, his classmates spat on and ostracised him. He saw Hitler break the law with impunity when he marched on Morgenthau's hometown, Coburg. Morgenthau concluded that abstract ideals could not protect him and that power only yielded to countervailing power. Fleeing to the United States in 1937, he became that country's most influential international relations scholar. When his peers lined up behind the Vietnam War, Morgenthau made a stand, dismantling the case for war on realist grounds.

Meticulously researched and masterfully written, The Realist shows how Morgenthau's ideas continue to shape the twenty-first century. Amid growing international disorder and the reemergence of great power competition in Europe and Asia, his realism is more relevant than ever.

David M. Sacks is a fellow at the Council on Foreign Relations. An expert on China and Taiwan, he has written for The New York Times, The Wall Street Journal, The Economist, Foreign Affairs, Time and the BBC, among other outlets. He lives in New York with his family.