“International politics, like all politics, is a struggle for power.” Hans Morgenthau wrote this sentence from his desk in Chicago at the dawn of the Cold War, as the United States and the Soviet Union embarked on an open-ended competition for global dominance. Politics Among Nations, the volume that Morgenthau ultimately produced, would quickly become the most widely adopted international relations textbook in the United States and provide an intellectual framework—realism—that would guide generations of scholars and policymakers.

Although much has changed in the nearly eight decades since Morgenthau’s most influential work was published, the fundamentals remain the same. Human nature, which for Morgenthau drove the struggle for power, is unmoved. States are still the most significant actors in the international system and compete for influence. Great powers continue to drive the course of history.…