Heraclitus was a rich man from Ephesus and lived c.500, during the Persian occupation
of his home town.
His philosophical work consists of a series of cryptical pronouncements that force a reader to think. 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.
