The paper will study an unpublished 1930–31 seminar where Heidegger reads Plato’s Parmenides, showing that in spite of his much-criticized habit of dismissing Plato as the progenitor of “idealist” metaphysics, Heidegger was quite aware of the radical potential of his later dialogues. Through a temporal account of the notion of oneness (to hen), the Parmenides attempts to reconcile the plurality of beings with the unity of Being. In Heidegger’s reading, the dialogue culminates in the notion of the “instant” (to exaiphnēs, (...) Augenblick)—a high point in the entire metaphysical tradition—where the temporal plurality of presence and un-presence converges into a unified disclosure. (shrink)