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Thales of Miletus

Thales of Miletus was a pre-Socratic Greek philosopher, mathematician, and astronomer who was born in the town of Miletus c. 624 BC and died c. 548 BC. He was one of the Seven Sages of Greece. Thales is recognized as the first philosopher in the Greek philosophical tradition, and he is historically recognized as the first individual in Western civilization known to have entertained and engaged in scientific philosophy.

Thales is also recognized for being one of the first philosophers to explain natural objects and phenomena using theories and hypotheses (instead of mythology), in a precursor to modern science. Aristotle regarded him as the founder of the Ionian School.

What is Thales known for? The influence and legacy of Thales of Miletus.


According to Herodotus, Thales predicted the solar eclipse of May 28, 585 BC. Thales also described the position of Ursa Minor and thought the constellation might be useful as a guide for navigation at sea. He calculated the duration of the year and the timings of the equinoxes and solstices. He is additionally attributed with the first observation of the Hyades and with calculating the position of the Pleiades.


Thales was known for his innovative use of geometry. His understanding was theoretical as well as practical. Thales understood similar triangles and right triangles, and what is more, used that knowledge in practical ways. There is a story told that he measured the height of the pyramids by their shadows at the moment when his own shadow was equal to his height. Thales used the same method to measure the distances of ships at sea.

Thales’ theorems

There are two theorems of Thales in elementary geometry, one known as Thales’ theorem having to do with a triangle inscribed in a circle and having the circle’s diameter as one leg, the other theorem being also called the intercept theorem. In addition, Eudemus attributed to him the discovery that a circle is bisected by its diameter, that the base angles of an isosceles triangle are equal and that vertical angles are equal.


Thales’ cosmological thesis was his most famous philosophical position was his cosmological thesis, Aristotle in his Metaphysics, reported Thales’ hypothesis about the nature of all matter – that the originating principle of nature was water.

Influence and legacy

Thales is recognized by most philosophers as having brought something new to human thought. Mathematics, astronomy, and medicine already existed, but Thales added something to these different fields to produce a universality, which, as far as writing tells us, was not in tradition before, but resulted in a new field. Philosophy.

Thales had a profound influence on other Greek thinkers and therefore on Western history. Pythagoras visited Thales as a young man and that Thales advised him to travel to Egypt to further his philosophical and mathematical studies.

Many philosophers of his time followed Thales’ lead in searching for explanations in nature rather than in the supernatural. Those who returned to supernatural explanations hid them in the language of philosophy rather than of myth or of religion.

Looking specifically at Thales’ influence during the pre-Socratic era, it is clear that he stood out as one of the first thinkers who thought more in the way of logos than mythos. The mythical man explains the world around him based on gods and mythical powers. Mythical thought does not differentiate between things and persons and furthermore, it does not differentiate between nature and culture. The way a logos thinker would present a world view is radically different from the way of the mythical thinker. Logos is a way of thinking not only about individualism but also the abstract focused on sensible and continuous argumentation. This sensible and continuous argumentation lays the foundation of philosophy and its way of explaining the world.