Thales

“...the first man in history to whom specific mathematical discoveries have been attributed.” Boyer in A History of Mathematics

Thales in a stamp together with the amber or ilektron that is able to attract other objects if charged

Philosophy among the Greeks is believed to have begun in the Ionian city of (ca 330 BC) Mathematical Intelligencer v. 6, no. 3, 1984.

He is also credited with the discovery of the electrical properties of amber (or “electron” from which also the name electricity was derived). He was one of the to argue that Thales and the other Seven Wise Men were enthusiasts of the Spartan culture.

The common tale among the Greeks was that Thales accompanied Croesus as a military engineer in his campaigns. The Ionians, noted engineers, were employed by the eastern kings, and Thales supposedly diverted the Halys river for his employer. The Ionian philosophers sought the material principle (arche) of things, and the mode of their origin and disappearance.

It is known that Thales was asked by his mother Kleobulina to get married. He was not very interested and his reply was: O Mother I am too young to marry. This he repeated for many years until some day, when his mother again asked him to marry he replied:
Mother now it is too late! When he was asked why he has no children his reply was: “Because I love children!” (Diogenes Laertios)

He divided tha year in 365 days according to Dioegenes Laertios who also has written that Thales died in the stadium looking some athletic game. When the visitors left they found that Thales remained there looking as sleeping. He was actually dead. Thales died in the 58^th Olympiad period (548-545 BC)

According to Proclus to Thales we owe several propositions later included by Euclid in his Elements. Thales is probably the first Greek mathematician to demonstrate or prove that:

• The angle in semicircle = 90 degrees, ,

  There is the anecdote of Thales the Milesian and his financial device, which involves a principle of universal application, but is attributed to him on account of his reputation for wisdom. He was reproached for his poverty, which was supposed to show that philosophy was of no use. According to the story, he knew by his skill in the stars while it was yet winter that there would be a great harvest of olives in the coming year; so, having a little money, he gave deposits for the use of all the olive-presses in Chios and Miletus, which he hired at a low price because no one bid against him. When the harvest-time came, and many were wanted all at once and of a sudden, he let them out at any rate which he pleased, and made a quantity of money. Thus he showed the world that philosophers can easily be rich if they like, but that their ambition is of another sort. He is supposed to have given a striking proof of his wisdom, but, as I was saying, his device for getting wealth is of universal application, and is nothing but the creation of a monopoly. It is an art often practiced by cities when they are want of money; they make a monopoly of provisions.
  

Lunar Crater Thales