 Hippasus is the first figure in the Pythagorean tradition who can with some confidence be identified as a natural philosopher, mathematician and music theorist. His connections are as much with figures outside the Pythagorean tradition as those within it. This independence may explain why neither Aristotle nor the doxographical tradition label him a Pythagorean, but he is too deeply embedded in the traditions about early Pythagoreanism for there to be any doubt that he was in some sense a Pythagorean. Aristotle pairs Hippasus with Heraclitus as positing fire as the primary element (Metaph. 984a7) and this pairing is repeated in the doxography that descends from Theophrastus (DK I 109. 5–16), according to which Hippasus also said that the soul was made of fire. Philolaus, who was probably two generations later than Hippasus, might have been influenced by Hippasus in starting his cosmology with the central fire (Fr. 7). For Philolaus, however, the central fire is a compound of limiter and unlimited, whereas Hippasus is presented as a monist and does not start from Philolaus’ fundamental opposition between limiters and unlimiteds.