Scholars in both international relations and political theory have been turning their attention to Thucydides with increasing frequency but with dissimilar questions. We draw on both traditions of inquiry to reexamine Thucydides' view of Pericles. We argue that antithetical reasoning is present in the treatment of Pericles and is manifested in the opposition between the statesman's brilliance and the infelicitous consequences of his statecraft, as become evident in the work as a whole. This antithesis undermines the claim advanced by certain figures in the History, as well as by contemporary realists, that states (statesmen) should not be held to the same moral standards as individuals because to do so subverts their capacity to conduct prudent policy. We propose that Thucydides' work suggests, instead, that it is precisely when the norms of moral conduct are disrupted that states and individuals find it next to impossible to chart a prudent course of action.