Bach: Prelude and Fugue No.12 in F minor, BWV 857 Analysis



Bach Prelude and Fugue No.12 in F minor BWV 857 Analysis 1


Bars 1-12: Period I. Tonic Pedal (Bars 1,2). Touches the Sub-dominant minor (B flat) (Bar 5), and the Relative Major (Bar 7). Ending with a Perfect Cadence in the Dominant.

Bars 13-22: Period II. Dominant Pedal (Bar 17-21). Ending in the Tonic, with Major 3rd.


This Prelude is built upon the figures as seen in the first bar above.

The principle melody is seen in crotchets (quarter notes), and at the opening is supposed by notes of similar length in the Tenor. The ornamentation in semiquavers (sixteenth notes) is made up chiefly of Arpeggios, Passing and Auxiliary notes being also employed.

Period I many be divided into two sections at Bar 9, the Cadence being to the Relative Major (A). Period II may also be divided at Bar 16, at which point there is a Deceptive Cadence, the opening subject being introduced and proceeding upon the Dominant Pedal.



Bach Prelude and Fugue No.12 in F minor BWV 857 Analysis 2



Bars 1-4: Subject in Tenor [F minor].
Bars 4-7: Tonal Answer in Alto, with Counter-subject I in Tenor [C minor].
Bars 7-10: Counter-subject II in Tenor.
Bars 7-10: Subject in Bass. Counter-subject I in Alto [F minor].
Bars 10-13: Codetta formed from Counter-subject I.
Bars 13-16: Subject (instead of the usual Answer) in Treble. Counter-subject I in Bass. Counter-subject II in Alto [F minor].
Bars 16-19: Episode I, modulating from F minor to C minor.
Bars 19-22: Subject in Tenor. Counter-subject I in Alto, transferred to Treble. Counter-subject II in Alto (Bar 19).


Bars 22-27: Episode II, modulating from C minor to F minor sequentially.
Bars 27-30: Subject in Bass. Counter-subject I in Tenor. Counter-subject II in Treble [F minor].
Bars 30-34: Episode III, modulating from F minor to A flat major.
Bars 34-37: Subject in Alto. Counter-subject I in Treble. Fragment of Counter-subject II in Tenor [A flat major].
Bars 37-40: Episode IV, modulating from F minor to E flat Major.
Bars 40-43: Real Answer in Tenor. Counter-subject I and Counter-subject II absent except by short reminiscences [E flat major].
Bars 43-47: Episode V, modulating from E flat Major to C minor.
Bars 47-50: Subject in Treble. Counter-subject I in Alto. Counter-subject II in Tenor [C minor].
Bars 50-53: Episode VI, modulating from C minor to F minor.


Bars 53-56: Subject in Bass. Counter-subject I in Treble. Counter-subject II absent [F minor].
Bars 56-58: Coda. Final chord major. Tierce de Picardie.


Exposition: Bars 1-16.
Counter-exposition: None.
Stretti: None.
Episodes: SIx, all closely allied by use of figures taken from the first Counter-subject and the Codetta.
Coda: Bars 56-58.


  1. This Fugue has a “tonal” Answer in the Exposition, and will therefore be called a “tonal” Fugue.
  2. The order in which the voices enter in the Exposition is unusual, as the Subject and Answer do not regularly alternate, but follow each other in the order: Subject, Answer, Subject, Subject; a Codetta being placed between the last two entries.
  3. The Construction of the Episodes is as follows:
    1. Episode I is mainly built upon the first two beats of the Counter-subject I taken in contrary motion.
    2. Episode II is built much the same as the first, but the melodic figure used in the Treble of the former is transformed to the Alto.
    3. Episode III is formed from the Codetta with the addition of a new vivacious figure in the Treble.
    4. Episode IV is formed in the two upper parts from the Counter-subject I (the Tenor rests), with a running counterpoint in the Bass part.
    5. Episode V is on a more extended scale than Episode IV, and all four voices take part in it. The Tenor has a detached figure taken from the second bar of the Counter-subject II.
    6. Episode VI is built upon the same melodic figures as Episode I, with which it should be compared.
  4. The Episodes are placed between each separate entry of the Subject and Answer, instead of – as is usual – between each group of entries.
  5. After the Exposition the Principle Theme appears six times only during forty-two bars, the large space thus alloted to the Episodes proving their great importance in the the scheme of this remarkably interesting Fugue.