Noctave
The piece
This little prelude is built on broken chords. For three bars the right hand spreads them out above a C held in octaves by the left hand; then the roles swap, and the left hand takes over the arpeggios while the right hand sings in long notes. Further on, the bass settles on G, and a quick scale just before the end drives the close. The text used here comes from volume 36 of the Bach-Gesellschaft edition, prepared by Ernst Naumann in 1890.
The arpeggio is the first challenge: the right hand must rise and fall in even eighths without the thumb marking each turn. Listen for the B-flat in the first bar, which colours the C chord and points toward the F that follows. The bass then alternates low and middle G in quarter notes, a repeated octave leap to make without looking. Six mordents decorate the score; place them on the beat with a quick gesture. Finally, the sixteenth-note scale goes down and back up, so settle the thumb crossing before you speed it up.