Chopin.

With rock music, there are certain expected structures in chord progressions, melodies, rhythms, and harmonies that make the music exciting. You can point to certain bands that managed their own primal versions of these structures: Nirvana and the dynamic verse-to-chorus transition, Neil Young's epic solos over minimal chord changes, GBV's potent distillations of melody. If, like me, you come of age on this stuff, it's your first musical language, but it can fail you in other genres

The first music outside the pop/folk/rock idiom I "got" was Baroque music -- Bach, to be specific. Only later did I consciously realize that the key to the music was the elaboration of the lines that the composer pulls through rough harmonic territory on the journey back to the tonic. Curiously, this metaphor also helps with jazz.

For Mozart and Beethoven, the idea of distance from the tonic ended up being the gateway, only now the music is conceived in terms of tall vertical chords rather than lines.

I have trouble with Chopin; I'm not quite sure what he's doing. A friend suggests that the ebb and flow of harmonic complexity in his music provides a sort of second-order melody: an elaboration through time of a single harmonic idea. I'm still trying to get my head around this, but this video seems like evidence for the theory.