Much of the meaning inherent in musical form comes from expectations aroused by reading the program.
What do you expect of a sonata? a symphony?
How is that different from an opera?
There has to be an element of irony unearthed when our expectations are not satisfied by actual experience. Perhaps that irony is what turned minuets into scherzi, and what makes Haydn's sonatas and symphonies such unending delights as he turns the most solid procedure on its head.
A beautiful case in point is the great Schubert B-flat Piano Sonata. B-flat is one of the most solidly stable tonalities on the piano--indeed, until the invention of the piano keyboard sonatas were rarely in that key. As I recall performances of the work they invariably indulge in that stability, fully pronounced in the opening chords. That is like a story opening the words "Period. The end" and proceeding to repeat them seemingly interminably.
What are the hints that Schubert is interested in elements that will disturb rather than reinforce that stability? First is that first accidental, E-natural, which I observe to be Schubert's favorite note. Second is the mysterious tempo marking: molto moderato, which I take to indicate, as also in the G-major, Op. 79 sonata, with discretion, not pre-determined..
