Thales of Miletus
624 BC - 547 BC
Thales of Miletus was born about 624 BC in Miletus, (now Turkey) and died there about 547. It seems that he is the first known Greek philosopher and mathematician and was believed to have been the teacher of Anaximander - another important Greek philosophers from the Milesian School.
No writings of Thales survived, so we are relying completely on what others have written about himself and his work. Proclus, the one of the later major Greek philosophers who lived around 450AD wrote that Thales went to Egypt as a young man and brought back what he learnt there into Greek philosophy and mathematics. He discovered many propositions himself, and instructed his students to question any and all mathematical problems. In this way they would deduce the general rule which can then be applied to any case to which the problem relates. This is now generally used in both mathematics and philosophy.
Thales is credited with five theorems of elementary geometry:-
i A circle is bisected by any diameter.
ii The base angles of an isosceles triangle are equal.
iii The angles between two intersecting straight lines are equal.
iv Two triangles are congruent if they have two angles and one side equal.
v An angle in a semicircle is a right angle.
See more about Greek mathematics.
Thales was not the last Greek mathematician and philosopher who learnt from Egyptians. Who do you think followed his example?
See more about other mathematicians here.
Or just climb the mathematical tree and see what branch you end up on!