Diatonic, he heard the word in his head. Chromatic, pentatonic, hexatonic, heptatonic, octatonic, each iteration of the scale opening innumerable possibilities for harmony. He thought about the Pythagorean major third, the Didymus comma, the way the intervals sound out of tune rather than as though they were different notes. This, he thought, was where his brilliance at mathematics bled into his love of music; music was the realm in which his mathematical brain danced.