Along with Solon, Thales of Miletus (624-546 BC) in Asia Minor was regarded by Plato as one of the seven sages of Greece. Thales sought to explain the origin and nature of the world without resorting to myths and gods, which is why he is often regarded as the first genuine philosopher, as well as the first genuine scientist. He held that all things are one, that water is the basic constituent of the universe, and that the earth floats on water like a log on a stream.
Thales was a geometer who travelled to Egypt to receive instruction from Egyptian priests. Whilst in Egypt he measured the height of the pyramids by measuring their shadows at the time of day when his own shadow was as long as he was tall. He discovered that triangles with one equal side and two equal angles are congruent, and applied this knowledge to calculate the distances of ships at sea. He also discovered the method for inscribing a right-angled triangle into a circle, and celebrated by sacrificing an ox to the gods, which he believed were in all things (‘all things are full of gods’).
He was also an astronomer and a meteorologist who determined the dates of the summer and winter solstices and predicted the solar eclipse of 585 which halted the Battle of Halys between the Lydians and the Medes. One year he predicted a good harvest of olives, took a lease on all the olive presses in Miletus, and made a fortune, simply to prove to his fellow Milesians that a philosopher could easily be rich, if only he did not have better things to do with his life. He was legendary for his absent-mindedness, and is probably responsible for our image of the philosopher as a scatterbrain or daydreamer. In the Theaetetus, Plato recounts that,
Thales was studying the stars and gazing into the sky, when he fell into a well, and a jolly and witty Thracian servant girl made fun of him, saying that he was crazy to know about what was up in the heavens while he could not see what was in front of him beneath his feet.
Thales was succeeded at the head of the Milesian School by his pupil Anaximander (610-546 BC)…
Adapted from Plato’s Shadow