The author contends that the differences between the original and published versions of Heidegger’s “What Is Metaphysics?” lie in how they understand the Nothing. Whereas the published version conflates the Nothing with Being as no thing, or simply sees the Nothing as a characteristic of Being’s finitude, the original version examines the Nothing on its own terms. Being, even if finite, still maintains continuity with beings as the Being of those beings. The Nothing itself, in contrast, marks a break with beings and their Being. The way in which it is interrogated must therefore also differ from the approach of the sciences and from ontology. If ontology, as a scientific account of Being, still bears a resemblance to the sciences generally, Heidegger’s study of the Nothing as such in the original version leads him beyond not just the notion of philosophy as a rigorous science, but even the possibility of rational argumentation.