No. 13 in F-sharp Major, BWV 858: Prelude

This prelude possesses immense beauty. There is nothing more regrettable than playing this prelude mechanically. It is undoubtedly a prelude that should be sung out fully. This prelude tends to become vertically segmented music if not handled carefully. Ingenuity is required to make it flow horizontally. However, the dotted eighth notes in the left hand mercilessly mark the beginning of each beat. These “dotted eighth notes marking the downbeats of a 4/4 measure” are a cause for the vertical segmentation, but not the only one. The left hand is written to mark the beat precisely where the right-hand voice is sustained. This makes the sustain of the right-hand voice inaudible, leading to the perception of vertical segmentation.

In pieces where notes in the left and right hands appear alternately like this, one must be careful to significantly reduce the volume of one of the voices. For example, look at measure 2. In the right hand (treble clef), there are three eighth notes spanning beats 1-3. Each eighth note should ideally be sustained until the next sixteenth note, but the left hand enters at that very moment. If the left hand is played loudly, it will obscure the right-hand voice.

Therefore, I believe it is best for the left hand to reduce its volume, and for the performer and student to play while “confirming the sustain” of the right-hand eighth notes and continuously listening to the sound.

From this point on, the discussion will be subjective. We will move on to explanations for each section. The arpeggiated theme in the right hand and the corresponding theme in the left hand, which appear in measure 1, are written in several places throughout this prelude. The first place to make a break is the first right-hand note, A-sharp, in measure 4. This note is considered a resolution of the B from the previous measure, so it should be played p as if fading away. Before that, the right hand reaches D-sharp in measure 2, which is likely the loudest point. After that, apply a diminuendo as the bass descends, reaching A-sharp in measure 4. From measure 4, the bass ascends, increasing the tension slightly, leading to a cadence in measure 5, and modulating to C-sharp major in measure 6.

Once modulated to C-sharp major, let's try to differentiate the atmosphere slightly from F-sharp major. C-sharp major might have a more brilliant and robust image. The descending bass after the theme (measures 7-9) and the later ascending bass (measure 11) are similar to the previous F-sharp major example. However, this time it modulates to a minor key, so the atmosphere will differ. A C double-sharp appears, which becomes the leading tone of D-sharp minor, leading to the D-sharp minor theme in measure 12, but it quickly modulates to A-sharp minor (measure 15). Then to G-sharp minor, and thereafter, the keys change dizzyingly. Performers should differentiate the mood of each key, giving them different colors, and always be aware of where they are on the “mountain”.

Fugue

Despite being such a joyful fugue, it is often played with a somber tone for some reason.

From measure 7 onwards, observe the sixteenth-note figure. This figure continues throughout the entire fugue. It conveys a restless joy, so be careful not to let the performance lack energy.

The theme begins in measure 1 and extends to the first note, an eighth-note A-sharp, in measure 3. Thereafter, fragments of this theme appear frequently. The first major break is likely on the downbeat of the third beat in measure 11. In measure 20, the theme modulates to D-sharp minor in the bass. Other sections involve repeated sequences, finally returning to the F-sharp major theme (measure 31) and concluding.

Regarding this sixteenth-note figure, I will explain using measure 12 as an example. Here, the figure appears in the bass. Look at beat 2. The notes are A-sharp, F-sharp, F-sharp, A-sharp, but in the next beat, they are B, F-sharp, F-sharp, B, and in the following beat, C-sharp, F-sharp, F-sharp, C-sharp, so the interval gradually widens. In this case, the dynamics should naturally crescendo as the interval widens.

And for articulation, apply legato to groups of two notes from the downbeat, creating two units per beat (A-sharp-F-sharp, F-sharp-A-sharp, B-F-sharp, F-sharp-B, etc.).