Ancient Greek philosophy had been going strong for a couple of hundred years before Socrates appeared on the scene. The primary thrust of their investigations was to discover the arche or first principle of all reality. Pythagoras (570-495 BC) and his followers were fascinated with numbers and explained all of reality in terms of numerical relations. A number of early philosophers tried to "reduce" reality to one or another of the four "elements," fire, air, water, or earth. Thales (flourished 585 BC), acknowledged as the first ancient Greek philosopher, had declared that all is water. Anaximenes (flourished around 545 BC) opted for air. Heraclitus (flourished 500 BC) had proposed fire as the first principle, though other aspects of his philosophy make the first principle a universal reason. Other, abstract, principles were the One (Parmenides, about 515 to about 445 BC), the Infinite (Anaximander, about 612-545 BC), and an infinite swarm of atoms (Leucippus, flourished 450-420 BC).
