Donald Kagan's magisterial history of the Peloponnesian War is recognized as a landmark of classical scholarship. Now, Kagan-one of the most respected classical historians in the world-turns his attention from one of the greatest conflicts in history to the author who so magnificently chronicled it: Thucydides, the first truly modern historian. This study offers readers a remarkable opportunity to experience one great historian engaging another across the centuries, in a work that is at once an engrossing voyage of discovery, a moving tribute, and a revelatory meditation on the practice of history and its value in human affairs.