b. =Fire is the Cosmic Substance.= Here we come to a difficulty in explaining the doctrine of Heracleitus because of the confusion in his own mind. He evidently goes a long way toward conceiving the cosmic substance as an abstraction――as the process of change. But he could not be wholly abstract. He stops and tells us that the cosmic substance is fire, and he probably means by fire just the same sort of thing as Anaximenes meant by air. Fire is the cosmic substance. It is the essence of all material things because it is the most mobile. But, after all, the fire of which Heracleitus is thinking is not a localized thing, like the fire on the hearth. For the hearth fire in a sense is ever identical with itself. The fire which Heracleitus means is ever darting, ever transforming material. To sum up: Heracleitus does not mean by fire an abstraction like the law of change; he does not mean, on the other hand, a material ever remaining like itself: he does mean a material, but a transforming material. c. =The Definite Changes of Fire.= Heracleitus makes some acute observations about the characteristics of the changing fire. The Milesians had been content to observe atmospheric changes and to name condensation and rarefaction as the forms of cosmic change. Heracleitus goes farther and emphasizes definite relations of change. The succession of changes always remains the same. Their definite relation is the only permanence in the world, and Heracleitus’ conception foreshadows the modern conception of the uniformity of the law of nature. The changes are (1) fateful, (2) rational, and (3) just. They show that the world is a destiny, a reason, and a justice. This identification of ethical and logical qualities with the physical betrays the undeveloped condition of the thought of Heracleitus.