Prelude Opus 28 No. 20 by Frédéric Chopin

Prelude Opus 28 No.20, often called the "Chord" prelude. Brief, with large slow quarter-note chords in the right hand predominating, against quarter-note octaves in the left. It was originally written in two sections of four measures, although Chopin later added a repeat of the last four measures at a softer level, with an expressive swell before the final cadence.