The composition of the work began as a few improvisational thoughts on a short phrase from a Beethoven piano sonata, which eventually developed into a six-minute fantasia that ultimately bears little audible relation to the original Beethoven phrase. The work is in four sections, of which the first and last are nocturnal, prelude, and postlude respectively. The main second section grows from a simple imitative idea to a chordal climax that subsides into a chorale and soliloquy which is elegiac in nature.
