Allegro in the Classical period refers to a quarter-note-based meter, not to a particular mood. In the F- minor Impromptu, D. 935, No. 1, in 4/4 Schubert specifies Allegro moderato. Assuming, as I did in the past, that this meant a quarter-note pulse throughout, I found myself bored with the repeated four-note accompaniment figures in the middle section.
Then it occurred to me that, in this case, moderato might mean "depending on the circumstances." If one allows the pulse to fluctuate to 3/16 in the accompaniment, the oddly irregular melodic fragments (usually consisting of three eighth notes, incidentally) become inherently poignant without any superficial emotion. The more I approach the work in this manner the more powerful it becomes.
Surely it is no coincidence that the arpeggiated triads between sections, played in 3/16, recall the arpeggiated chords of the Moonlight Sonata.
Boredom while playing Schubert is often the key that opens the magical lock to indescribable treasures.
