Bars 1-14: Period I. Ending in the Dominant Minor, C sharp.
Bars 14-24: Period II. Passing though B minor, the to C sharp major – its own Dominant, it works home to the original key (Bar 22).
Bars 22-24: Coda. Using the 1st and 3rd parts of the Theme and again firmly grasping the Tonic key.
The material used almost exclusively throughout this Prelude is take from the Theme first given in the Treble, which is elaborated, and which for convenience of analysis has been divided into three portions.
Period I ends at Bar 14, and not at Bar 12 as might be imagined, the passage between these bars is merely again returning to the same key (C sharp minor), and only serves to more fully confirm the Cadence already made at Bar 12.
Both Periods are capable of subdivision: Period I dividing at Bar 7 (Cadence in Relative Major) and Period II at Bar 19 (Cadence in Domina
Bars 1-4: Subject in Tenor [F sharp minor].
Bars 4-7: Real Answer in Alto, with Counter-subject in Tenor [C sharp minor].
Bars 7-8: Codetta.
Bars 8-11: Subject in Bass. Counter-subject in Alto [F sharp minor].
Bars 11-15: Codetta.
Bars 15-18: Subject in Treble. Counter-subject in Bass [F sharp minor (irregular)].
Bars 18-20: Episode I, modulating from F sharp minor to C sharp minor.
Bars 20-23: Answer by inversion in Alto. Counter-subject absent [F sharp major].
Bars 23-25: Episdoe II, modulating from F sharp to C sharp minor.
Bars 25-28: Answer in Treble. Counter-subject in Alto. Close in C sharp minor [C sharp minor].
Bars 28-29: Codetta.
Bars 29-32: Subject in Tenor. Counter-subject in Treble [F sharp minor].
Bars 32-35: Subject by Inversion in Bass. Counter-subject absent [F sharp minor].
Bars 35-37: Episode III, modulating sequentially from F sharp minor to A major, and back to F sharp minor.
Bars 37-40: Subject in Treble. Counter-subject in Alto, with which the Fugue concludes. Tierce de Picardie.
Exposition: Bars 1-18.
- This Fugue has a “real” Answer, and would be called a “real” Fugue.
- The order in which the voices enter in the Exposition is unusual, being Subject, Answer, Subject, Subject, instead of the usual Subject, Answer, Subject, Answer. The Exposition is also unusually long, owing to the extent of the Codettas introduced.
- The device of Inversion is used on two occasions, Bars 20 and 32. There is no Augmentation or Diminution.
- The fugue of the Counter-subject is very characteristic and prominent throughout.