Thales of Miletus

Thales of Miletus was an early Greek thinker from the Ionian city of Miletus in Asia Minor and is traditionally regarded as the first philosopher in Western intellectual history. Celebrated as one of the Seven Sages of Greece, he was credited in antiquity with initiating a new mode of inquiry that sought to explain the natural world through rational investigation rather than mythology. Eighteenth-century historians further elevated his status as the founder of Greek philosophy, mathematics and natural science.
Thales proposed that the underlying principle (archē) of nature was water, a view that influenced subsequent Milesian philosophers. He held that the Earth floated on water and attempted to account for natural phenomena in material terms. His reputation in mathematics, astronomy and engineering grew through accounts of practical accomplishments such as measuring the height of pyramids, determining the distance of ships at sea and diverting a river to assist an army. Classical writers also credit him with predicting a solar eclipse and identifying astronomical markers such as Ursa Major and the solstices.

Life

Knowledge of Thales’s life derives largely from the third-century CE writer Diogenes Laertius, whose Lives and Opinions of Eminent Philosophers preserves earlier traditions but is chronologically distant and sometimes unreliable. Thales was a native of Miletus, a prosperous trading city near the mouth of the Büyük Menderes River in modern Turkey. Most ancient and modern sources place his floruit around the late seventh and early sixth centuries BC. Herodotus links him to the famous solar eclipse traditionally dated to 585 BC, and chronographers therefore estimate his birth around 625 BC.
His ancestry is uncertain. Some ancient authors, citing Herodotus and others, describe him as belonging to a Milesian family of Phoenician descent, while alternative views emphasise exclusively Greek origins. Modern scholarship generally considers him a Milesian of distinguished local lineage, though mixed ancestry is possible given the cosmopolitan character of Ionia.
Biographical anecdotes present him as either married with a son or unmarried but adopting his nephew Cybisthus. One well-known story records Solon questioning his decision to remain single, to which Thales replied with varying explanations depending on his age and circumstances.

Travels and Cultural Context

Archaic Greece maintained strong cultural exchange with Egypt and the Near East, and later writers commonly attributed foreign travels to early Greek thinkers. Traditions suggest Thales engaged in trade and visited Egypt or Babylonia. Although direct evidence is lacking and widely debated, Miletus had established ties with Egypt through the colony of Naucratis, making such travel plausible. Reports that he learned geometry from Egyptian priests were popular in antiquity, though some historians argue he may have acquired knowledge indirectly.
Similar claims of Babylonian influence arise in connection with mathematical techniques and astronomical systems such as the sexagesimal base. Some modern historians accept Babylonian contributions to early Greek science, while others contend that key systems were unknown in Greece until the Hellenistic period. Herodotus reported that the Greeks adopted the gnomon and the division of the day into twelve parts from Babylonia, though scholars note that these practices also existed in Egypt and may have developed independently in Greece.

Sagacity and Wisdom

As one of the Seven Sages of Greece, Thales became associated with moral and practical wisdom. The canonical list of sages varies, but always includes Thales, Solon, Pittacus and Bias. According to Diogenes Laertius, this group was recognised at Athens around 582 BC. Each sage was associated with a Delphic maxim inscribed at the Temple of Apollo. Thales’s most famous saying was “know thyself”, a precept interpreted as a caution against pride and an invitation to self-examination. Later writers debated its authorship, and some attributed it to mythical or priestly figures, but the association with Thales remained enduring.

Anecdotes and Legends

Ancient sources preserve numerous stories highlighting Thales’s ingenuity and moral standing. One widely repeated tale involves a golden tripod or bowl meant to honour the wisest person. According to Callimachus, the gift circulated among the sages before returning to Thales, who dedicated it to Apollo at Didyma.
Thales also earned a reputation in political counsel. Diogenes Laertius recounts that he advised the Milesians to avoid an alliance with Lydia, which enhanced his standing as a prudent statesman. In another account, Plutarch praises Thales for elevating philosophy from abstract speculation to practical application through engineering works such as diverting the Halys (Kızılırmak) River.

Contributions to Mathematics and Science

Thales is associated with several geometrical discoveries, forming the basis of what later became known as Thales’ theorem, which states that an angle inscribed in a semicircle is a right angle. He is also linked to the intercept theorem, which deals with proportionality in intersecting lines. These attributions reflect early Greek efforts to develop deductive reasoning in geometry.
Reports of Thales’s astronomical achievements include identifying Ursa Major, determining the solstices and equinoxes, and forecasting weather patterns—though the historicity of predicting the 585 BC eclipse remains debated. His approach to natural phenomena, grounded in material causes rather than divine agency, marked a pivotal shift in the history of science.