PYTHAGORAS c.575  c.490 BC Greek Philosopher 

Pythagoras was a Gk philosopher and mathematician, best known for
working out the "Pythagorean Theorem" stating that the square of the
hypotenuse of a rightangled triangle is equal to the sum of the squares
of the other two sides.
Pythagoras was born on the island of Samos, migrated to southern Italy, and established a school at Croton. Pythagoras taught that the order of the world was to be discovered with the aid of mathematics, physics, acoustics and astronomy. His famed saying was "all is number" meaning that all existing things can be ultimately reduced to number relationships. His mystical teaching accepted the migration of souls. 
www link : Encyclopedia of Philosophy Biography
From the University of St.Andrews, Scotland  School of Mathematics 