Philolaus (c.470–380/9 BC)

The Greek philosopher Philolaus of Croton, a contemporary of Democritus and Socrates, was a pre-eminent Pythagorean. His book counts as the first written treatise in the history of Pythagoreanism. Surviving in fragments, it constitutes an important source for our knowledge of fifth-century Pythagoreanism and supplements the picture given by Aristotle of Pythagorean doctrine.

Like earlier Presocratics Philolaus sought to furnish a comprehensive cosmology. Arguing from logical propositions, he posited two pre-existing principles: ‘unlimited things’ and ‘limiting things’. United by harmony these two principles account for the formation of the cosmos and its phenomena. Since Philolaus also invokes number as an all-powerful explanatory concept, it is likely that he associated his first principles and the things originating from them with numbers. The emphasis on harmony and number accords with early Pythagoreanism.

Philolaus also wrote on musical theory and astronomy. A noteworthy feature of his astronomy is the displacement of the earth from the centre of the cosmos by fire, pictured as the ‘hearth’ of the universe. The fragments further attest Philolaus’ interest in embryology, the causes of diseases, and physiology combined with psychological functions.

It was not unusual for early Greek philosophers to treat such a wide variety of topics. The distinctive elements of the thought of Philolaus are the logical arguments evinced in the fragments and the epistemological role of number for understanding the structure of reality.