Because we are so sure of what happens when we push buttons we are out of touch with the possibility that things happen in the interstices between touching and pushing those buttons.
We learn chord progressions. Then someone comes along who has never learned chord progressions and introduces wonderfully off-beat details into what might otherwise pass for a standard harmony.
That off-beat detail grabs me. I look for it every time I hear the live performance of the song but it always moves around, or is it that there were always several such details and I caught only one the first time and am now catching a different one?
The great thing is that I'll never know. I have to keep going back and listening for more.
That is what all good music making should be about, whether the piece was composed two days or two hundred years ago.
Constant variation, no matter how "familiar." Keep it (and yourself) moving.
