I think chords and notes were chosen to create harmony. Or at least, the key was picked and the concepts used (mode, arpeggiation) will stay in it. Listening to

I think chords and notes were chosen to create harmony. Or at least, the key was picked and the concepts used (mode, arpeggiation) will stay in it. Listening to it carefully, there is no random generation at all. It's all deterministic and periodic.