I've been doing a massive re-evaluation of Schubert the last couple of months and listening to more of his songs sung by Dietrich Fischer-Dieskau has just accelerated the process. I'm afraid that in the past I have not given Schubert his full due. His working life was a mere eighteen years but in that time he composed a thousand pieces of music--well, actually 998 opus numbers (or Deutsch numbers after the compiler) many of which include several pieces. During his lifetime Schubert was much-appreciated by the Viennese, but largely in the context of domestic music-making where his songs and piano pieces were often heard in a salon setting. The most familiar of his public music were his choral settings such as this one for male choir:
But for a good example of the kind of effect that Schubert achieved with his piano music have a listen to the Moment Musical #6.
If you listen closely, or even better, have a look at the score, you can hear/see that what Schubert is up to is using those harmonies that previously gave music its greatest dynamic impetus instead to move music to another plane. The effect is to linger, to pause, to live in the moment--the very opposite of the way Beethoven might have used these harmonies, to drive the music on, to depict a kind of heroic effort. The harmonies I mean are the flat submediant and the Neapolitan. Both of these harmonies are remote from the tonic and previously were used to prepare a strong movement to the dominant which then, of course, goes to the tonic. But Schubert is using them as places to rest, places of stability, but remote from the tonic. The analogy is to another world, the private world of meditation, of subjectivity. The key of the piece is A flat major so the flat submediant is F flat. This is where the second phrase starts, with no preparation. Suddenly introducing a remote harmony and staying on it is a major harmonic innovation of the Romantic period and it was Franz Schubert who first used these harmonic devices in this way.