Owing to the towering influence of Thucydides, classical Athens enjoys an extraordinary reputation for the clear-sighted and openly expressed pursuit of advantage in its foreign policy. In particular, Realist scholars and students in the discipline of International Relations, preparing others or themselves eager someday to serve their own nation's interests, admire the Athenians' precise and complex calculations of expedience and envy them their frankness. Consequently, Thucydides appears on lists of canonical Realist texts alongside such twentieth-century classics as Edward Carr, The Twenty Years' Crisis: 1919–1939 and Kenneth Waltz, Theory of International Politics. A prudent foreign policy, free of self-serving cant and hypocrisy and immune to the emotions of anger and hatred, has an obvious appeal. And, indeed, a significant strain in Athenian thinking about the relations of states did possess these characteristics. Even as we paint a more complete, and inevitably more complex, picture of Athenian thinking and even as we explore the limitations of using interests as a guide to conduct, we should keep in mind two points: first, the attractions of a calculating policy are real and significant; second, we would not be studying Athenian thinking about foreign policy at all were it not for the Athenians' attempt, however doomed, to subject it to rational calculation; for this, as much as anything else, distinguishes their thinking.