The cause of great power war is a perennial issue for the student of politics. Some 2,400 years ago, in his monumental History of the Peloponnesian War, Thucydides wrote that it was the growth of Athenian power and the fear that this power inspired in Sparta which rendered the Peloponnesian War somehow necessary, inevitable, or compulsory. In this new political psychological study of Thucydides' first book, S.N. Jaffe shows how the History's account of the outbreak of t...