In May 1985, I gave a talk based on chapter 5 of this book to a seminar at the Institute of Classical Studies in London. My host introduced me as someone who was about to do the opposite of what Thucydides did, by leaving history for politics. I replied that I hoped to show that for Thucydides, as for me, to do history was to do politics, and vice versa.

The tale of how I came to see Thucydides' task – and my own – in this way is a long one, peopled with many remarkable friends and teachers. As a student at Yale, I was interested in politics but had little understanding of what politics was about or what it was for. A course on the origins of war, ancient and modern, taught with singular energy and vision by Donald Kagan, persuaded me that the study of ancient politics and political ideas would help me to understand how people think and behave politically. Don Kagan guided me in my first encounter with Thucydides, and he has been mentor and valued friend ever since.

The Andrew W. Mellon Foundation made it possible for me to spend two years at Clare College, Cambridge studying the classics. When I return there to write a Ph.D. on Greek political ideas, I was welcomed back by Clare College.