There is a long and successful scholarly tradition of commenting on Nietzsche’s deep affinity for the philosophy of Heraclitus. But scholars remain puzzled as to why he suggested at the end of his career, in Ecce Homo, that the doctrine he valued most, the eternal recurrence of the same, might also have been taught by Heraclitus. This essay aims to answer this question through a close examination of Nietzsche’s allusions to Heraclitus in his first published mention of eternal recurrence in (...) The Joyful Science and in a related set of notes from the period when he was formulating and defending his doctrine of eternal recurrence while writing Thus Spoke Zarathustra. The key to answering this question, it is argued, is that Nietzsche came to believe that the doctrine of eternal recurrence, when properly understood as requiring identical repetition, has to presuppose a Heraclitean reality of eternal, absolute, and universal flux. (shrink)