International relations scholars are prone to claiming that the ancient historian of the Peloponnesian War, Thucydides, is a realist of one kind or another. Paul Viotti and Mark Kauppi tell us that Thucydides “is usually credited with being the first writer in the realist tradition as well as the founding father of the international relations discipline.” Michael Doyle writes, “To most scholars in international politics, to think like a Realist is to think as the philosophical historian Thucydides first thought.” Kenneth Waltz found in Thucydides an expression of his “third image,” in which the balance of power states find themselves in largely determines their actions. Robert Keohane and Joseph Nye use Thucydides as a representative of their “overall power model” or the “traditional” international relations paradigm. Both classical realists, who begin with an understanding of human nature, and neorealists, who emphasize the international structure, can find support for their theoretical viewpoint in Thucydides.