Thales of Miletus (circa 635 BC - 543 BC) was a pre-Socratic Greek philosopher.
He is generally considered the first philosopher in the Greek tradition and is considered the father of science as well. He is numbered among the Seven Sages of Greece.
Thales is remembered for arguing that water is the essence of all things. This argument is significant because it is the first attempt to explain the physical world without reference to a supernatural power. Prior to Thales all such explanations relied on gods or other mythological forces. Furthermore, he knew that the earth was a ball, that the moon reflects light from the sun, and, according to Herodotus, he forecasted the solar eclipse in 585 BC.
Thales lived in the city of Miletus, in Ionia. The Ionians were well-traveled and had many dealings with Egypt and Babylon, and it is possible that Thales had studied in Egypt as a young man. In any event, Thales was almost certainly exposed to Egyptian mythology, astronomy, and mathematics, as well as other traditions alien to the Homeric traditions of Greece. It is perhaps because of this that his inquiries into the nature of things took him beyond traditional mythology.
Thales had a profound influence on other Greek thinkers and therefore on Western history. Anaximander is sometimes considered to be a pupil of Thales. And it is reported by early sources that one of Anaximander's more famous pupils, Pythagoras, visited Thales as a young man, and was advised to travel to Egypt to further his philosophical and mathematical studies. Many philosophers followed his lead in searching for explanations in nature rather than in the supernatural; others returned to supernatural explanations, but couched in the language of philosophy, rather than myth or religion.
Herodotus reports that in 585 BC Thales was with the Lydians when they fought the Medes, and was able to forecast that a solar eclipse would occur on May 28 which ended the war (see Alyattes II).
A famous, though contradictory, anecdote of his life involves a business decision. He is said to have been able to predict the weather, and bought all of the olive presses in Miletus when he knew there would be a good harvest. Another version states that Thales bought the presses because the Milesians wondered why he didn't use his intelligence to make himself wealthy. Other versions say he bought the wine presses, rather than the olive presses.
See also: Thales' theorem
Thales Group has been the name of the French electronics and defence contractor Thomson-CSF (Compagnie de telegraphie Sans Fil) since 2000.