  The standard view of Heraclitus’ ontology since Aristotle is that he is a material monist who holds that fire is the ultimate reality; all things are just manifestations of fire. According to Aristotle the Milesians in general were material monists who advocated other kinds of ultimate matter: Thales water, Anaximander the boundless, Anaximenes air (Metaphysics 983b6–984a8). So Heraclitus’ theory was just another version of a common background theory. There are problems already with Aristotle’s understanding of the Milesians: Aristotle lacks any textual evidence for Thales’ view and must reconstruct it out of almost nothing; he sometimes treats Anaximander as a pluralist like Anaxagoras who thinks the boundless is a mixture of qualities; at most Anaximenes might exemplify material monism–but Plato reads him as a pluralist (Timaeus 39 with Graham 2003b; Graham 2003a). In the case of Heraclitus, his own statements make material monism problematic as an interpretation. According to material monism, some kind of matter is the ultimate reality, and any variation in the world consists merely of qualitative or possibly quantitative change in it; for there is only one reality, for instance fire, which can never come into existence or perish, but can only change in its appearances. Heraclitus, however, advocates a radical kind of change: