Eclipse of Thales (585 BC): The Birth of Greek Philosophy

Thales of Miletus, a Greek thinker of the sixth century BC, is famous for reportedly foretelling the total solar eclipse that halted a battle between Lydia and Media, most probably on 28 May 585 BC. The story made him the most celebrated wise man of his age. More importantly, Thales tried to explain the world through natural causes rather than myth, and for this Aristotle named him the founder of natural philosophy.

Miletus and its world

Miletus was a wealthy Greek city on the coast of Ionia, in what is now western Turkey. It traded across the Aegean and the Black Sea and had close contacts with the kingdom of Lydia inland and with Egypt and the Near East. This mix of trade and foreign learning made it a natural birthplace for new ideas.

Thales was probably born around 624 BC and died around 546 BC, according to dates handed down by the ancient chronographer Apollodorus. Herodotus says his ancestry was partly Phoenician, though most writers treat him as a Milesian Greek. He was counted first among the Seven Sages of Greece.

The eclipse

Herodotus reports that Lydia, under King Alyattes, and Media, under King Cyaxares, had been at war for five years when day suddenly turned to night in the middle of a battle. Both sides stopped fighting and made peace. Thales, he says, had foretold this change to the Ionians, naming the year in which it occurred. The battle itself is described in Battle of the Eclipse.

Modern calculations show that a total eclipse crossed Anatolia on 28 May 585 BC, which matches the year given by Pliny the Elder. How Thales could have predicted it is much debated. Babylonian astronomers kept long records of eclipses, preserved in sources such as the Babylonian Astronomical Diaries, and knew of cycles after which eclipses tend to recur. Thales may have learned of such a cycle and judged that an eclipse was possible in a given year.

Predicting where a solar eclipse would be visible, however, was beyond anyone’s knowledge at the time. Many scholars therefore think the prediction was either a lucky estimate or a story that grew after the event.

Water and a world without myth

Thales’ lasting importance lies in his questions rather than his answers. According to Aristotle, writing about two centuries later, Thales held that water was the arche, the original source of all things, and that the earth floats on water like a piece of wood.

These ideas sound strange today, but they mark a change of method. Instead of explaining the world through the actions of gods, as in the poems of Homer and Hesiod, Thales looked for a single natural substance underlying change. He may have been influenced by observations that life depends on moisture, and perhaps by Near Eastern myths of primeval waters.

Aristotle also reports two other sayings: that “all things are full of gods” and that the magnet has a soul because it moves iron. These suggest that Thales saw the natural world as alive and active.

Stories of Thales

Thales attracted many anecdotes. Herodotus says he was believed to have diverted the River Halys so that King Croesus of Lydia could cross it, although Herodotus himself doubted this. He also reports that Thales advised the Ionian cities to form a single council at Teos to resist outside conquest.

Aristotle tells how Thales, mocked for being poor and useless, foresaw a large olive harvest from his study of the stars and rented all the olive presses in advance, making a fortune to show that philosophers could become rich if they wished. Plato tells the opposite kind of story: Thales, gazing at the stars, fell into a well, and a Thracian servant girl laughed at him.

Later writers said he measured the height of the Egyptian pyramids by their shadows and proved several theorems in geometry. These claims appear only long after his death and should be treated with caution.

The Milesian school

Thales’ successors in Miletus continued his search. Anaximander proposed that everything came from an unlimited substance he called the apeiron, and Anaximenes argued that the basic substance was air. Historians group the three as the Milesian school, the first stage of what is often called Presocratic philosophy.

Anaximenes was still active after Persia absorbed Ionia following the conquest of Lydia in the 540s BC, but Miletus itself was sacked by the Persians in 494 BC after the Ionian Revolt. The tradition passed westward, where thinkers such as Pythagoras carried Greek philosophy to southern Italy.

Timeline

• c. 624 BC: Thales is born in Miletus (date from Apollodorus, approximate).
• 28 May 585 BC: A total solar eclipse halts a battle between Lydia and Media, as Thales reportedly foretold.
• c. 560 BC: Croesus becomes king of Lydia; later stories link Thales to his campaigns.
• c. 547 BC: Cyrus of Persia conquers Lydia, and Ionia soon falls under Persian rule.
• c. 546 BC: Approximate date of Thales’ death.
• 4th century BC: Aristotle describes Thales as the first natural philosopher.

Why it matters

Thales is the first person in the Greek tradition remembered for trying to explain nature by nature. His eclipse prediction, whatever its real basis, became a symbol of a new kind of knowledge drawn from observation and calculation. Western philosophy and science both trace a line back to the questions he asked in Miletus.