The great Pythagorean oath was taken by the sacred tetractys.
The Pythagorean school of philosophers adopted the theory of a spherical earth, but from metaphysical rather than scientific reasons; their convincing argument was that a sphere being the most perfect solid figure was the only one worthy to circumscribe the dwellingplace of man.
He is described as the eighth leader of the Pythagorean school, and was a pupil (not the teacher, as some have maintained) of Philolaus.
Hippocrates, influenced as is thought by the Pythagorean doctrines of number, taught that they were to be expected on days fixed by certain numerical rules, in some cases on odd, in others on even numbers - the celebrated doctrine of "critical days."
The Pythagorean and Eleatic systems of philosophy had their chief seat in Magna Graecia.