This is a four-voice fugue, written with great complexity. It is easy to overlook the themes, so careful attention is advised. In measure 1, it is difficult to distinguish whether this voice is the soprano or the alto. The first four measures initially appear to be soprano and alto, but the line entering from the off-beat A in measure 7, beat 1, seems to be the soprano.

Assuming the theme in measure 1 extends to A on beat 3 of measure 4, the next theme emerges from G on beat 2 in the bass clef in measure 5. Next, from D in the soprano in measure 10 to G on beat 1 of measure 12. From D in the tenor on beat 4 of measure 11, it moves to the treble clef in measure 13.

Thus, themes do not always begin on beat 2; they can also start on beat 4, as in measure 11, and there are also fragments of themes.

The sub-theme begins from D in the lower voice of the treble clef in measure 3 and extends to the half note G on beat 1 of measure 5.

The performer should:

• First identify all theme-like passages.
• Next, identify the sub-themes.

Generally, points where the volume increases correspond to passages where the hands move apart. Furthermore, when a theme is in a lower register, imagine the sound of thick pipes on a pipe organ (e.g., from G in the bass on beat 4 of measure 30).

Since there are no distinct peak points, the performer should grasp the themes and determine the dynamics by considering which themes have higher tension, among other factors.