Chopin's Prelude #4 (measures 5 - 9)

In the second beat of measure 8, Chopin uses an auxiliary diminished 7^th to prepare the IV⁶ in measure 9 (the chord is completed by the G# in the right hand). Note also the appoggiatura (a ninth) in the upper voice (B - A) in measure 9.

Chromatic movement can be summarized as follows:

Middle voice - Chromatic passing tones (F# - F - E).

Lower voice - Chromatic and diatonic passing tones.

Some of the interesting chords that are produced by the chromatic movements are a diminished 7^th chord (D# dim7) in measure 6 (2^nd beat) and a dominant 7^th chord (D7) in measure 7.

In measures 10 to 12, Chopin moves between IV and V. The first part of the prelude ends in measure 12 with a half cadence.