The centrality of the national interest to Morgenthau's political realism is well known yet often lamented for its lack of clarity. This article offers a grammatical reading in order to highlight the Platonic and Aristotelian roots of the metaphysical assumptions that inform the national interest in Morgenthau's work and to show that, despite his continuous injunctions against the dangers of utopianism, he fails to escape them himself. Ultimately, his attempts to insulate us against the possibility of totalitarianism leads us back into its violent embrace via a ‘mysticism’ that defines a role for the nation-state as the embodiment of eternal moral truths and values.