[1] The work was originally titled Etude fantastique en double-sons (Fantastic Study in Double Notes), and was infamously referred to by Schumann as the "hardest piece ever written"—to this day it remains as "one of the most ferociously difficult pieces in the piano repertoire".
[2][3] A series of alternating chords introduce the main theme.
The development features rapid unison octaves and counterpoint.
A typical performance of this piece (with the repeat sign observed) can last anywhere from six to eight minutes.
It is partially based on the Czerny Toccata in C major, Op.