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Thinkers

Thales of Miletus

Ancient Greek · Europe · 624 to 546 BCE

Early Greek thinker from Miletus who looked for natural causes and said that everything comes from water.

What it is

Thales was a Greek thinker from Miletus, a city on the coast of Asia Minor, whose life ran from the seventh into the sixth century BCE. He is often called the first philosopher in the Western tradition, because he is credited with offering natural explanations of the world in place of stories about gods.

His exact dates are uncertain, and accounts differ by a few years on both his birth and his death. He left no surviving writings, so what we know of his ideas comes mostly from later writers, above all Aristotle.

The main ideas

  • Everything comes from water. Aristotle reports that Thales took the first principle of things to be water, a single material from which everything is made. Thales' own words are lost, and Aristotle only guessed why he chose it.
  • The earth floats on water. He is said to have held that the earth rests on water and floats on it.
  • Looking for causes inside nature. He never put the organisation or control of the cosmos in the hands of the gods. He looked for explanations within nature itself, and this is the main reason he is called the first philosopher.
  • A soul in a stone. Aristotle reports that Thales thought a lodestone has a soul, since it makes iron move, and that everything is full of gods. What he meant is not clear.
  • Geometry. He is credited with early work in geometry, including results about circles and triangles, and with measuring the height of a pyramid.

What it looks like in practice

Picture someone standing by a river after a flood, asking why the bank has moved and the field has grown. A follower of Thales would not look for an angry god, but for something in the water and the earth that could account for it. This is an illustration of the approach he began, not a story about him.

Books and moments

  • The eclipse. Thales is said to have foretold the solar eclipse that darkened a battle between the Lydians and the Medes, dated to 585 BCE. How he could have done it is argued over.
  • The Seven Sages. He is counted among the Seven Sages of Greece, a group of wise men remembered from ancient times.
  • Lost writings. Ancient reports credit him with a few works, but it has always been doubted whether he wrote anything at all.
  • Egypt. Some ancient authors say he travelled to Egypt and learned geometry there. Whether he really went is disputed among scholars.

Questions and criticism

  • What did he mean by water? Aristotle records the claim and then offers his own ideas about how Thales might have reasoned. Whether water was one stuff among others or the source of all stuffs is a question left open.
  • How much is Aristotle's? Because we depend on a writer who came long after, it is fair to ask how much of the idea is Thales' and how much comes from Aristotle's way of telling the story.
  • Did his explanations work? The idea that the earth floats on water was later replaced by other accounts, and it is fair to ask whether the kind of explanation he looked for matters more than the answer he gave.

Close neighbours

The pages on Anaximander and Anaximenes, who also lived in Miletus, are the nearest, since they followed him in looking for the first principle of things. The page on Heraclitus and the page on Aristotle, who reports his ideas, are close as well.

Written by epchē in our own words, and checked against independent sources on 29 October 2026. The sources are listed below.

Who they connect to

Influenced

  • Anaximander · Anaximander is traditionally named as his pupil and successor in Miletus.

Other Ancient Greek thinkers

Sources we used

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