The Pythagoreans... were fascinated by certain specific ratios, ...The Greeks knew these as the 'golden' proportion and the 'perfect' proportion respectively. They may well have been learned from the Babylonians by Pythagoras himself after having been taken prisoner in Egypt. Ratios lay at the heart of the Pythagorean theory of music.
Graham Flegg, Numbers: Their History and Meaning
golden-ratio, history-of-mathematics, music, numbers, pythagoreans