Philosopher and Greek mathematician. Philosopher of nature, Thalès was the first to try to give an explanation rational, and nonmythological, universe.

He extended his activity to physics, mathematics and astronomy as well as with philosophy.

Counted one of the Seven Wise ones of Greece, he was regarded by Aristote as the founder of Ionian natural philosophy.  

The legend claims that he predicted the eclipse of the sun of 585 av. J. - C., which put an end to a battle between Mèdes and Lydiens; but this prediction is incompatible with the state of astronomical knowledge of the time. That it acquired its mathematical knowledge in Egypt seems quite as improbable, being given the difference between the level of Egyptian mathematics at the time and that of the demonstrations of Thalès. One lends to him, for example, the rigorous demonstration of the division of the circle in two equal parts by a diameter, whereas this theorem is not shown nearly three hundred years later by Euclide.

One also allots the resolution of the problem of the inscription of a triangle in a circle and the method to him to measure the height of an object starting from his shade: method from where one will draw the famous theorem from Thalès on the parallel straight lines cut by two other lines (“any parallel with the one on the sides of a triangle divides the two other sides into segments proportional”).

It is him also which would have the noticed first that certain ores of the Magnesia area have the property to attract iron. For him, the paramount element of which all the universe comes is water, a water on which fleet a ground punt.