, third movement Oster observes that the
Fantaisie-Impromptu draws many of its harmonic and tonal elements from
Beethoven's
Moonlight Sonata, also in C minor, especially the third movement. Two measures after the melody sets in, an abrupt run features the same notes, only one octave higher, as the cadenza in the sonata's third movement (Presto agitato). The climax on a Chord inversion| chord is similar in both pieces. Additionally, the
Fantaisie-Impromptus middle part and the second movement of the
Moonlight Sonata are in D major. The first and third movements are in C minor. For those and other reasons, Oster writes, "Chopin understood Beethoven to a degree that no one who has written on the C minor Sonata or the
Fantaisie-Impromptu has ever understood him. ... The
Fantaisie-Impromptu is perhaps the only instance where one genius discloses to us—if only by means of a composition of his own—what he actually hears in the work of another genius." The piece uses many
cross-rhythms (the right hand plays
sixteenth notes against the left hand playing
triplets) and a ceaselessly moving note figuration, and is in
cut time (). The opening
tempo is marked
allegro agitato. The tempo changes to
largo and later
moderato cantabile when the key changes to D major, the
enharmonic equivalent of C major, that is, the
parallel major of C minor. The piece then changes to
presto (although some versions of the score incorporate a
coda, meaning that the original tempo of
allegro agitato is repeated) where it returns to C minor. It concludes with an ambiguous fantasy-like ending, with the left hand replaying the first few notes of the moderato section theme while the right continues playing sixteenth notes (semiquavers). The piece resolves and gently ends on a rolled C major chord (a
Picardy third). ==Legacy==