The Pre-Socratic Philosophers

Western philosophy began with Thales (~585 BCE), who thought everything was made of Water. He was succeeded by Anaximander (~546 BCE), who thought everything came from a mysterious primal substance, and Anaximenes (~494 BCE), who thought everything was made of Air. These three chaps lived in the city of Miletus, whose ruins are in modern day Turkey.

Pythagoras (~523 BCE) loved numbers and shapes; he came from the Greek island of Samos. Heraclitus (~500 BCE), who thought everything was made of Fire and the universe was an ever-changing Oneness, considered Pythagoras an idiot and was not a fan of Homer. He came from the city of Ephesus, whose ruins are in modern day Turkey.

Parmenides (~450 BCE) thought that there was no such thing as change, and that the universe was a never-changing Oneness. He came from the city of Elea, whose ruins are in modern day Italy.

Empedocles (~440 BCE) thought he was a god and, legend has it, threw himself into a volcanic crater to prove it. He was the chap who established Earth, Air, Fire, and Water as the Four Elements out of which everything was made. (He was, of course, totally unaware that his elements system would be used in countless fantasy stories and video games thousands of years after his death.) The Force of Love bound elements together and the Force of Strife broke them apart; the Universe is on an eternal Love-Strife cycle. He came from the city of Agrigento in Sicily, which still exists.

Leucippus (~440 BCE) and Democritus (420 BCE) are the two founders of Atomic Theory: the Universe is a mixture of the Void (nothingness) and tiny, physically indivisible Atoms. There are infinite atoms, and infinite types of atoms. The different properties of matter are the result of different combinations of these atoms. Atomism combined the theories of Parmenides and Heraclitus: each atom is a never-changing Parmenidean One, but the Atoms are constantly moving through the Void and mingling with other Atoms to produce an ever-changing universe. Leucippus came from the aforementioned Miletus; Democritus came from the city of Abdera, whose ruins are in modern day Greece.

(So many ruined cities...)

And then along came Socrates, if he existed at all, who showed everyone how philosophy was supposed to be done. (I hear philosophy picks up big time after Socrates; here's hoping.)

Source: A History of Western Philosophy by Bertrand Russell