Thales of Miletus

Lore & Background

Thales of Miletus was a pre-Socratic Greek philosopher from the Ionian city of Miletus, located in Asia Minor. He was counted among the Seven Sages of ancient Greece. From the eighteenth century onward, many historians viewed him as the first philosopher in the Greek tradition, marking a shift away from mythological explanations of the world toward natural philosophy. He is also considered the first to engage in mathematics, science, and deductive reasoning.

Thales proposed that all of nature is based on a single fundamental substance, which he believed to be water. He also thought that the Earth floated on water. In mathematics, both Thales’s theorem and the intercept theorem are named after him. He was said to have calculated the heights of the pyramids and the distance of ships from the shore.

Astronomy

As an astronomer, he reportedly predicted the weather and a solar eclipse. He is credited with discovering the position of the constellation Ursa Major, as well as the timings of the solstices and equinoxes. As an engineer, he enabled the Lydian army to cross the Halys River. Plutarch wrote that at that time, Thales alone had raised philosophy from mere speculation to practice.

Life

The main source for Thales’s life is Diogenes Laërtius, writing in the third century AD, though his work contains unreliable or fabricated information. Thales came from Miletus, a mercantile city at the mouth of the Maeander River, near modern Didim, Turkey. His birth date is roughly established by a solar eclipse he predicted in 585 BC, as recorded by Herodotus. Using the assumption that a person’s acme occurs at age forty, Apollodorus of Athens placed his birth around 625 BC.

Ancestry and family

Herodotus described Thales as a Phoenician by remote descent, and Diogenes Laërtius cited sources saying Thales was the son of Examyas and Cleobulina, belonging to the Thelidae, who were Phoenicians and descendants of Cadmus and Agenor. However, Friedrich Nietzsche and others interpret this to mean his ancestors were Cadmeians from Boeotia.

It is also possible he had mixed ancestry, as his father had a Carian name and his mother a Greek name. Most writers, however, represent him as a genuine Milesian of distinguished family. Encyclopedia Britannica concluded he was likely a native Milesian of noble birth and certainly Greek.

Diogenes reports conflicting accounts of Thales’s family life: one says he married and had a son named Cybisthus or adopted his nephew of the same name; another says he never married, telling his mother it was too early when young and too late when old. Plutarch tells a version where Solon asked Thales why he remained single, and Thales replied he did not want to worry about children, though he later adopted his nephew Cybisthus.

Travels

Thales may have traveled to Egypt or Babylonia, but there is no strong evidence for such visits, and the issue is disputed. Several ancient authors assume he visited Egypt, where he learned geometry, possibly from priests of Thebes. Miletus had a permanent colony in Egypt at Naucratis, making a visit possible. He may also have known about Egypt from others.

Babylonia was another advanced mathematical civilization, and some historians like Roger L. Cooke and B.L. Van der Waerden argue for Babylonian influence on Greek mathematics, citing the sexagesimal system, though this is controversial. Other historians, such as D. R. Dicks, dispute this, noting the sexagesimal system was unknown in Greece until around the time of Hipparchus. Herodotus wrote that the Greeks learned the gnomon from the Babylonians, and Thales’s follower Anaximander is credited with introducing it to the Greeks.

Reader's Guide

Thales is recognized as one of the Seven Sages of Greece. Diogenes Laërtius tells us that the Seven Sages were created in the archonship of Damasius at Athens about 582 BC and that Thales was the first sage.

The sages were associated with the Delphic maxims, a quote or maxim attributed to each one inscribed on the Temple of Apollo at Delphi. Thales has arguably the most famous of all, gnothi seauton or know thyself. According to the 10th-century Byzantine encyclopedia the Suda, the proverb is both 'applied to those whose boasts exceed what they are' and 'a warning to pay no attention to the opinion of the multitude.'