The conception of the formation and decay of the cosmos was given a different twist in Stoic doctrine. The views of the Stoic School were considerably influenced by the philosophy of Heracleitus (beginning of the fifth century B.C.), who, like Empedocles after him, regarded the harmony prevailing in the universe as the result of a dynamic equilibrium of opposite forces. For Heracleitus, this dynamics was built up round fire: "There is an exchange: all things for Fire and Fire for all things, like goods for gold and gold for goods." The sun and stars were created from, and are still fed by, the evaporation of the water on the surface of the earth; and this evaporation is brought about by the heat reaching the earth from the heavenly bodies. This double motion, upwards and downwards, is characteristic of the harmony of opposites whereby there is a simultaneous process of coming into being and decay within the existing cosmos.