PHILOLAUSKalabria, approx 475 B.C.
A philosopher of the Pythagorean academy, Philolaus was born either in Taranta, or according to Diogenes the Laertian, in Crotone of southern Italy. During the unrest following the death of Pythagoras, Philolaus escaped first in Lefkania and then to Theba in Greece. Later he returned in Italy, where there is a possibility that he was the teacher of another great philosopher, Archytas.
Philolaus was taught the famous Pythagorean theory of numbers and pointed the importance of numerical sums. He was particularly interest into number ten, a sum of the first 4 numbers, known as "tetraktys". Spefsippus, the heir of Plato in the Platonic academy is said to having the tetraktys dogma imported by a Philolaus' book.
Only extracts however are saved out of his work, along with the belief that he was the first organizing the Pythagorean theory into a method.