Noctave
The piece
Beethoven dedicated the Pathétique Sonata to Prince Karl Lichnowsky, one of his patrons in Vienna. Between two fast movements in C minor, this Adagio cantabile is a calm rondo: the theme is first stated in the middle register, then repeated an octave higher, and returns twice more, separated by two episodes. The second, in A-flat minor, grows more uneasy, with repeated chords in triplets that quicken the pulse. The final return of the theme keeps that triplet motion in the accompaniment.
From the first bar, the right hand does two things at once: it sings the melody with the outer fingers and plays a sixteenth-note accompaniment with the thumb. The whole movement rests on this: melody on top, accompaniment underneath, within one hand. The tempo is slow, 30 here, so you have to sustain the melody’s long notes and connect them without gaps. One note in five carries an accidental beyond the four flats of the key signature. The octaves, spread between the two hands, stay round, never harsh.