It reminds me of the tension between simultaneity and sequence in Shevek of Anarres' temporal theory; the part where he hasn't written it yet (The Dispossessed by Ursula LeGuin). I guess an arpeggio (particularly one where the notes are sustained) is a play/tension on the simultaneity of chords vs. the sequential melody of sounding the notes one by one. Harmonically, more than one key is there at the same time, it seems.