Pythagoras believed that mathematics and musical harmony were intrinsically linked. He discovered that consonant musical intervals had simple whole number frequency ratios, like octaves being 2:1 and perfect fifths being 3:2. Pythagoras used the first four whole numbers and their sum to represent this harmony in the symbolic figure of the tetractys, showing how unity emerges from the infinite through mathematical order and progression. This linked music, mathematics and the cosmos in a harmonic whole.