Actually an engineer, I am best known for my contributions to philosophy and mathematics.
I also dabbled in business and politics...bought all the olive presses after predicting the weather and wanting to control the expected harvest...not to become wealthy but to demonstrate how one's intelligence can enrich oneself.
In mathematics, I helped put geometry on a rigorous basis, shifting the emphasis from "how" to "why?"
Using ideas related to proportional sides of similar triangles, I measured heights of pyramids and found distances of ships from shore.
Eudemus credits me with 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.
A pre-Socratic philosopher from Miletus, I am considered one of the Seven Sages of Greece.
Thales of Miletus (ca. 624 BC – ca. 546 BC)