tl;dr: A programmer derives Western music theory from first principles using JavaScript and the Web Audio API, showing how the 12-note system emerges from reconciling powers of 2 (octaves) with powers of 3 (fifths), why equal temperament is a necessary compromise, and how scales, chords, and progressions reduce to arrays of integers. Along the way it explains consonance via overlapping harmonics, why major and minor differ by a single semitone, why V-to-I resolution works (the tritone inside the dominant 7th), and treats musical notation as a lossy serialization format with historical constraints.