Professor Emeritus of Classics and History at Yale University, Donald Kagan is a preeminent historian of both the ancient and modern worlds. In this conversation, Kagan and Kristol discuss what humanity's greatest wars—from the Peloponnesian War to World War II—can teach us about the nature of war and the sources of human conflict. Kagan also discusses his education in history at Brooklyn College, his groundbreaking work on Thucydides, and his distinguished teaching career at Yale. Finally, Kristol and Kagan discuss the state of the study of history and the liberal arts more generally in America today.