Heraclitus of Ephesus (c.500 BCE): one of the pre-Socratic philosophers of ancient Greece.
Heraclitus was a rich man from Ephesus and lived c.500, during the Persian occupation of his home town. Part of Heraclitus' activities may have been directed against the Persian Magians, whom he calls "wanderers of the night". His philosophical work consists of a series of cryptical pronouncements that force a reader to think: "war is the father of all things", "all things are in a state of flux and nothing is permanent", "the road up and down is one and the same".
Unfortunately, a great part of his work is lost, which makes it very difficult to reconstruct Heraclitus' ideas. It seems certain, however, that he thought that the basic principle of the universe was the logos, i.e. the fact that it was rationally organized and therefore understandable. Bipolar oppositions are one form of organization, but the sage understands that these oppositions are just aspects of one reality. Fire is the physical aspect of the perfect logos.