gadzooks
Dark Matter
[keratinize my mild-tasting blossoming]
Realize that it's all mathematical ratios. Chords, chord progressions, etc.
Middle C on the piano is a sine wave oscillating at 440 Hz. Every other key within that octave is proportionally higher (if C# and up) or lower (if A or B).
Harmony arises from certain biologically pleasing combinations of these notes.
From there it's just a matter of memorizing a finite set of chords and chord progressions.