Aristotle draws a distinction between the poets who concerned themselves with the gods versus the philosophers who concerned themselves with the investigation of nature. Having started with Hesiod the poet, we will now concern ourselves with Thales.

Thales is hailed as the first philosopher. He was a citizen of Miletus, an Ionian city-state on the coast of Asia Minor. His one claim that has come down through the ages is that the world consists of water. He did not seek to explain phenomena in terms of Zeus throwing thunderbolts or Hera getting jealous and thus causing it to storm. Rather, he imagined water, arranging and re-arranging as the cause of change in the world. This is a version of natural science. We know almost nothing about Thales, but he must have been a very daring man to break with the poets.

Anaximander was also a Milesian, and a younger contemporary of Thales. Anaximander is also concerned with finding natural causes of change in the physical world. But Anaximander posits a source of the world called “the Infinite.” Decidedly metaphysical compared to water, right? Out of the Infinite, he says, come the elements such as water, air, fire and earth. It is ageless and eternal and the source of all natural things. Then he goes on to describe the heavens and the earth, the planets, stars and their motion. You see here a mix of what we would call today metaphysics with natural science.