Postlude

In this prelude Chopin seems to have decided to experiment with two harmonic resources:

• II - V progression: We find it in measures: 1, 2, 3, 5, 6, 7, 13 a 14 (with a tonic chords in 2nd inversion between the chords), 15, 16, 17, 18, 19, 21 and used as a Neapolitan sixth chord in measures 24 y 33.
• Augmented sixth chord: The use of this chord as an enharmonic equivalent of a dominant seventh chord and the chromatic movement of dominant seventh / augmented sixth chords is probably the most important harmonic innovation in this prelude. We find it in measures 3, 4, 7, 8, and 22.