Measures 3 and 4

The next two measures are more interesting. The II-V progression from the previous measure is developed and used in measures 3 and 4 in the keys of C# minor and B minor. Note the chromaticism in these measures:

Recording courtesy of Robert Ståhlbrand and Piano Society

The dominant seventh chord on the fourth beat of bar 3 descends chromatically to another seventh chord (F#7 – F7). The F#7 chord can be analysed as a German augmented sixth chord (Gb – Bb – Db – E) of Bb. Note that the augmented sixth/minor seventh of the chord (E) moves downwards instead of upwards as in a normal augmented sixth. This is done to ensure that the seventh is present in the dominant seventh chord. The next example shows:

1. how a dominant seventh chord is transformed into a German sixth
2. how this chord would normally resolve
3. how Chopin uses this chord

Similar voice movements can be found in other examples of Romantic literature. However, what makes this example remarkable is that Chopin seems to have discovered the beauty of the parallel movement of chords. As we will see, he develops this technique in other sections of the prelude.

In the fourth measure, the diminished seventh chord of A minor transforms into a diminished seventh chord of F#, returning to the key of F# minor. Note that these two chords are enharmonically equivalent (G#-B-D-F = E#-G#-B-D):

The inner voice is also highly chromatic.