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Thales

Original nameThales of Miletus

Ancient Greek Philosopher, Acknowledged as the "First Philosopher of the West"

Remembered for a Single Line · Small Roles, Famous Names

The Milesian SchoolNatural PhilosophyThe Question of the First Principle

Who they are

Thales (c. 624–546 BC) was the founder of the ancient Greek Milesian school, retrospectively named by Aristotle in the Metaphysics as "the founder of philosophy," because he was the first known thinker to attempt to explain the origin of all things in the universe by causes in nature itself (rather than the will of the gods of myth). He proposed that "water is the first principle of all things," holding that all the manifold things of the world ultimately arise from the change and derivation of some single basic substance — this way of asking "what the world is made of" marks the first step of human thinking from mythical narrative toward a rationalized, systematic exploration of natural philosophy, and later Milesian successors such as Anaximander and Anaximenes carried on this path of inquiry into "the first principle of all things."

Primary sourcesAristotle’s relay of the early philosophers in the Metaphysics

Key stories

Predicting an Eclipse

According to the ancient Greek historian Herodotus, Thales successfully predicted the occurrence of an eclipse (modern astronomical calculation suggests possibly the eclipse of 28 May 585 BC); though the details are hard to fully verify, this account won him the lofty ancient reputation of a "sage versed in astronomy and the calendar," and is one of the earliest known cases of scientific prediction.

Falling Into a Well While Gazing at the Stars

Plato records an anecdote: Thales, absorbed in gazing at the stars to study the heavens, carelessly fell into a well by the road, and a Thracian servant-girl mocked him for "being so eager to know the things of the sky that he could not see what was at his feet." This story was thereafter often cited to tease the image of the philosopher lost in abstract speculation and cut off from everyday practical life, and, from the reverse side, to highlight the transcendent quality of philosophical inquiry "gazing at the stars."

Version differences

Thales left no writings of his own, and our understanding of his thought depends wholly on the relays and summaries of later philosophers such as Aristotle; most details of his historical life are also worked up through later legend.

Relationships

Disciple

🌀Anaximander　Anaximander was his student and carried on the Milesian tradition of seeking the first principle of all things

Echoes today

Below are how modern works borrow or reinterpret this name or story — not the original material. The two differ, so keep them apart.

"Thales’s theorem" (geometry)The "Thales’s theorem" in modern geometry textbooks (that an angle inscribed in a semicircle is a right angle) is named for him, one of the earliest named geometric proofs.

Appears in

The Pre-Socratics: From Myth to ReasonThales Proposes That "Water Is the First Principle of All Things"The Pre-Socratics: From Myth to ReasonAnaximander Proposes the "Boundless"

⏳ Who lived at the same time as Thales? →🔗 Who taught whom →

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