The early Greek philosophers of the Milesian school, which was founded by Thales of Miletus and later continued by his successors Anaximander and Anaximenes, were the first to attempt to explain natural phenomena without relying on the supernatural.[38] The Pythagoreans developed a complex number philosophy[39]:467–68 and contributed significantly to the development of mathematical science.[39]:465 The theory of atoms was developed by the Greek philosopher Leucippus and his student Democritus.[40][41] The Greek doctor Hippocrates established the tradition of systematic medical science[42][43] and is known as "The Father of Medicine".[44]