A word about the connection between those four terms:
Knowing in advance about tonal or chordal function I am less susceptible to the mystery of particular voicings or registers. I tend to be less interested in a predictable resolution than in a potential that is hinted but not spelled out.
This affects my sense of timing. I am by nature impatient. Let's get on with it, I seem to say to myself.
But what if the tempo indicates that a bit of reserve is called for? Put it differently: what if the tempo indicates that the music epitomizes reserve?
Going back over Schubert I am convinced that this is what he means by moderato. I might define it thus: It moves to a reliable beat except when it doesn't.
