Thales

c. 625 b.c.e.–c. 547 b.c.e.

Philosopher
Mathematician
Astronomer

The Founder of Greek Philosophy.

The Greeks looked upon Thales as the founder of Greek philosophy and the first man to attempt to provide a scientific explanation for the origin of the world. He was born in Miletus on the south-west coast of Asia Minor around 625 b.c.e. and in his youth he was an avid traveler. As Hieronymus of Rhodes indicates in his report, Thales measured the pyramids by their shadow, having observed the time when a person's shadow is equal to the person's height. It wasn't long after his trip to Egypt that Thales went to Greece to further his study of geometry. It was in Greece that he began to lecture on natural sciences and philosophy and he founded one of the first Greek schools of philosophy the Ionian School, also called the Milesian school.

Legend of Eclipse Prediction.

Thales was said to have predicted an eclipse of the sun which has traditionally been dated to 585 or 584 b.c.e. and if this report is true, it would provide the one certain date in his life. Whether he actually predicted the eclipse or not is a matter of dispute. At one time scholars believed that he used astronomical observations borrowed from Babylon to make his prediction, but it is now known that at this time, the Babylonians had no theory for predicting solar eclipses that Thales could have used. Moreover, the story goes that the eclipse that Thales predicted took place just as the Medes and the Lydians were about to fight a battle at the Halys River in Asia Minor, and the Milesians were present as allies of Lydia. The eclipse caused the Medes and Lydians to break off the battle. The story implies that the eclipse took place during daylight hours, and there was no solar eclipse at a suitable hour in 585 or 584 b.c.e., though on 21 September 582, there was a partial eclipse, three-quarters total at 10 and this may have been the eclipse which Thales was said to have foretold. Clearly Thales' prediction was a legend, but it is evidence of his reputation as an astronomer was among the Greeks.

Anecdotes about Thales.

There were a number of similar stories told of Thales' activities as engineer, mathematician, and astronomer, as well as a philosopher. When his critics derided his wisdom as impractical, he used his astronomical knowledge to predict a superabundant crop of olives, and made a fortune by cornering the market in olive presses. Another story which presented him as an absent-minded intellectual told that while he was stargazing, he fell into a well, and a servant girl who found him laughed at him because he failed to notice what was at his feet as he examined the heavens. He discovered that two triangles were equal if two angles and one side were equal and he evidently used this theorem to measure the distance of ships out at sea. He was credited with a book on navigation titled the Nautical Star Guide, but it is doubtful if he was the author of this work. Most scholars think that Thales wrote nothing.

Contribution to Natural Philosophy.

Thales argued that the material constituent of all things is water. The earth, he claimed, floats on water, and he used this theory to explain why earthquakes occurred. He rejected the explanation that they took place when a god such as Poseidon shook the earth. It is possible that he derived his theory from Near Eastern mythological explanations of creation, for Babylonian descriptions of the world order spoke of the "waters under the earth." Yet Thales' doctrine did not turn to supernatural or mystical explanations in order to understand natural phenomena. Instead of elaborating stories of how the universe came into existence, as Hesiod did in his Theogony which proposed a theological explanation for how the world arose from chaos, Thales posed a new question—"What is the universe?—and his answer was a theory based on observation of the real world. As such he paved the way for the development of modern natural science.

Helped Croesus During War With Persia.

When Thales was an old man, the Lydian kingdom, then ruled by Croesus, whose wealth was proverbial, was threatened by a new enemy, Cyrus, king of Persia, who had overthrown the last king of the Medes in 550 b.c.e. Croesus, whose sister had married the last king of the Medes, wondered if he should attack Persia before it grew too strong, and he consulted the oracle of Apollo at Delphi. The oracle gave the ambiguous answer, "If Croesus crosses the Halys River, a great empire will fall." Croesus imagined the prophecy was favorable and launched an attack, not realizing that his empire was the one destined to fall. Thales accompanied him, and another legend told that he helped the Lydians cross the Halys River by diverting part of the stream into another channel. Croesus was defeated, and in 547 or 546 b.c.e. his capital of Sardis fell to Cyrus. The Ionian cities that had been subject to Croesus wondered what to do, and Thales proposed that they should form a federal state and present a united front to Persia. But Cyrus split the Ionian resistance by offering Miletus a favorable alliance and leaving the conquest of the rest of Ionia to one of his generals. Following this event, Thales passed from the historical records until his death around 547 b.c.e.

sources

Robert S. Brumbaugh, The Philosophers of Greece (New York: Thomas Y. Crowell, 1964).

John Burnet, Greek Philosophy; Thales to Plato (London, England: Macmillan, 1950).

James Longrigg, "Thales," in Dictionary of Scientific Biography. Vol. XIII. Ed. Charles Coulson Gillespie (New York: Charles Scribers Sons, 1976): 295–298.

Erwin Schrödinger, Nature and the Greeks (Cambridge: Cambridge University Press, 1954).