Circa 540-Circa 480 B.C.E.
Philosopher

An Enigma. For the ancient world, Heraclitus (also spelled Heracleitus or Herakleitos) was always skoteinos, "dark" and "obscure." This reputation was due as much to his riddling, prophetic style as to the exact nature of the mysterious logos or reason he saw hidden beneath the flow and flux of appearances. Tradition has it that, despite the political privileges that came from his birth into one of the aristocratic families of Ephesus, he rejected leadership in favor of the life of a misanthropic hermit, living alone in the mountains, eating plants and grass. Haughty and aloof, rude and enigmatic, he was famous for his caustic wit and his rejection of most other thinkers as learned but far from intelligent or wise.

Fire. The one book that Heraclitus apparently wrote, On Nature, or Muses (circa 500 B.C.E.), is lost, and later scholars...