The peak of this Prelude can be considered the 21st measure, which is also the final measure. Of course, there are several climaxes leading up to it.

Understanding the Key

Before the analysis, let's understand the key of B-flat major. While B-flat major shares some similarities in mood with C major, it feels a step more brilliant and elegant than C major. Consider works like Invention No. 14, Sinfonia No. 14, or the Well-Tempered Clavier. It is by no means a key with a strong character like F major. Please consider B-flat major to be a gentle and dignified key.

Detailed Analysis

Let's begin with the opening. Based on a B-flat pedal point, the right-hand melody ascends along a scale. It reaches the highest note, B-flat, on the third beat of measure 2. Let's give it a sense of direction up to that point. In measure 3, it descends in a sequence, so apply a gradual diminuendo, reaching the third beat of measure 4. However, on the second beat, the right-hand melody ascends along a scale. How to treat this section is up to the performer. Since these are small notes, it might be advisable to avoid a sudden crescendo.

On the third beat of measure 4, it modulates to F major, and the theme appears. It appears in the left hand, also ascending, reaching the highest note, F, on the first beat of measure 5. Whereas before it descended in a sequence from that point, this time it ascends, and on the fourth beat, E becomes E-flat, returning to B-flat major. This section feels somewhat unsettled, likely due to the absence of a stable bass note. The bass playing the melody contributes to this unstable feeling.

The bass, with its intricate movements, modulates to G minor on the fourth beat of measure 8. In measure 11, it modulates back to F major. From measure 12, the dominant of F major continues. This prolonged dominant also creates a sense of unease; one desires to resolve to the tonic. The tonic is reached, after a cadence, on the first beat of measure 14.

From there, there's a hint of E-flat major, but it returns to B-flat major in measure 16. However, from measure 17, the bass once again plays the melody. One even senses that something significant is about to happen. Measures 17-18 clearly have the feel of the dominant of B-flat major; here, not only does the dominant persist, but the bass also plays the melody, creating a superposition of "two unsettling elements." While the prolonged dominant again creates a sense of restlessness, a cadence is reached on the fourth beat of measure 18, leading to measure 19, where it truly returns to B-flat major, playing the same melody as in measure 1 from the tonic chord.

However, from the third beat of measure 19 onwards, the number of notes increases, the texture thickens, leading to a dramatic ending, as if all the stops of a pipe organ are pulled out and sounding at full volume. This is what was previously mentioned about heading towards measure 21.

While the dynamics are at the performer's discretion, please use the preceding analysis as a reference to structure your performance of the piece.