Bach: Prelude and Fugue No.22 in B♭ minor, BWV 891 Analysis

Analysis

Prelude

Bach Prelude and Fugue No.22 in Bb minor BWV 891 Analysis 1

SUMMARY:

Bars 1-24: Period I. Ending with a Perfect Cadence in the key of the Tonic Minor, B flat.
Bars 21-41: Period II.Ending with a Perfect Cadence in the key of the Relative Major, D flat.
Bars 41-55: Period III. Ending with a Perfect Cadence in the key of the Subdominant Minor, E flat.
Bars 55-70: Period IV. Ending with a Perfect Cadence in the key of the Tonic minor, B flat
Bars 70-83: Coda. Firmly establishes the Tonic key. Dominant Pedal (Bars 73-77).

REMARKS:

This Prelude is built mainly upon Theme 1 (Bars 1-5), which is notable form its character and extent, extending as it does to Bar 5. In the course of the Prelude it is used in the following keys:

  1. In Bar 1 and onwards in the Alto part in the Tonic Minor (B flat).
  2. In Bar 8 and onwards in the Treble part of the Dominant Minor (F).
  3. In Bar 25 and onwards in the Bass part in the Tonic Minor (B flat).
  4. In Bar 31 and onwards in the Treble part in the Relative Major (D flat).
  5. In Bar 42 and onwards in the Bass part (but transferred to the Alto at Bar 44) in the Dominant of the Relative Major (A flat).
  6. In Bar 48 and onwards in the Alto part (transferred to the Treble at Bar 50) in the Subdominant Major (G flat).
  7. In Bar 55 and onwards in the Treble part in the Subdominant Minor (E flat).
  8. In Bar 62 and onwards in the Alto part in the Tonic Minor (B flat).

The first six notes of Theme I are used momentarily in Bars 5,6 (Bass part) by Inversion.

A new short Theme in quavers (eighth notes) (Theme II), little more than a bar in length, appears at Bar 7 (Alto Part), and it does a remarkable amount of work throughout the Prelude, in its original and inverted forms it appears no less than forty-seven times, being the great factor in all the Episodal work between the entries of the Great Theme, and also frequently appearing with it.

The Coda is built chiefly upon the material of Theme II, used in both similar and contrary motion.

Fugue

Bach Prelude and Fugue No.22 in Bb minor BWV 891 Analysis 2

ANALYSIS:

ENUNCIATION SECTION:

Bars 1-5: Subject in Alto [B flat minor].
Bars 5-9: Real Answer in Treble, with Counter-subject in Alto [F minor].
Bars 9-11: Codetta.
Bars 11-14: Subject in Bass, with Counter-subject in Alto [B flat minor].
Bars 15-17: Codetta.
Bars 17-21: Answer in Tenor, with Counter-subject in Bass [F minor].
Bars 21-27: Episode I, modulating from F minor, through D flat major to B flat minor.
Bars 27-31: Subject in Tenor [B flat minor].
Bars 27-31: Stretto I, Answer in Alto [B flat minor].

MODULATORY SECTION:

Bars 31-33: Codetta, modulating from B flat minor to D flat major.
Bars 33-37: Subject in Treble [D flat major].
Bars 33-37: Stretto II, Answer in Bass [D flat major].
Bars 37-42: Episode II, modulating from D flat major to B flat minor [D flat major].
Bars 42-46: Answer in Tenor by Inversion, with Counter-subject in Alto also by Inversion [B flat minor].
Bars 46-50: Subject in Alto by Inversion, with Counter-subject in Tenor also by Inversion [E flat minor].
Bars 50-52: Codetta.
Bars 52-56: Subject in Treble by Inversion, with Counter-subject in Alto also by Inversion [B flat minor].
Bars 56-58: Codetta.
Bars 58-62: Answer in Bass by Inversion, with Counter-subject (second part) in Treble by Inversion [A flat minor].
Bars 62-67: Episode III, modulating from A flat minor, through E flat minor to B flat minor.
Bars 67-71: Subject in Tenor by Inversion [B flat minor].
Bars 67-71: Stretto III, Answer in Treble by Inversion [B flat minor].
Bars 71-73: Codetta.
Bars 73-77: Subject in Alto by Inversion [F minor].
Bars 73-77: Stretto IV, Answer in Bass by Inversion,
Bars 78-80: Codetta.
Bars 80-84: Subject in Treble by Inversion [A flat major].
Bars 80-84: Stretto V, Answer in Tenor [A flat major].
Bars 84-89: Episode IV, modulating through E flat minor to B flat minor.

RECAPITULATORY SECTION:

Bars 89 to 93: Subject in Bass [B flat minor].
Bars 89-93: Stretto VI, Answer in Alto by Inversion [B flat minor].
Bars 93-96: Codetta.
Bars 96-100: Stretto VII, Subject in Treble and Alto, simultaneously in 3rds [B flat minor].
Bars 96-99: Answer in Tenor and Bass, simultaneously in 3rds by Inversion [B flat minor].
Bars 100-101: Coda.

SUMMARY:

Exposition: Bars 1-21.
Counter-exposition: Bars 42-62.
Codettas: Eight.
Stretti: Five (Three complete, two incomplete).
Episodes: Four.
Coda: Bar 100-101.

REMARKS:

  1. This Fugue has a “real” Answer, and would be called a “real” Fugue.
  2. The Counter-subject is employed only in the first half of the Fugue, After Bar 60 it disappears altogether, its ground being taken up chiefly by Stretti of the Principle Theme.
  3. In the Exposition the Counter-subject is used exceptionally, being given to the Alto voice twice in succession (Bars 5 and 11), At Bar 11 we should have expected to find it in the Treble part.
  4. The Counter-exposition appears unusually late. This is caused by the fact of there being a complete Stretto after the first Episode, which, in the present case, necessitates another Episode after it, in order to make the requisite modulation before the Counter-exposition can enter. In this Counter-exposition the Theme is used in its Inverted form through all the parts. The Counter-subject also, though not used in its entirety, is subjected to the device of Inversion.
  5. All the Stretti are constructed at the distance of a minim (half note).
    1. Stretto I, the Answer is at the interval of the 7th below.
    2. Stretto II, the Answer is at the interval of the 9th below; this may be considered as a continuation of Stretto I, though a short Codetta stands between them. Thus considered the four entries form one complete Stretto
    3. Stretto III, the Answer is at the interval of the 9th above.
    4. Stretto IV, the Answer is at the interval of the 7th below. The same remark applies to these Stretti as Nos. I and II. All the parts being Inverted, these together would form a complete Stretto by Inversion
    5. Stretto V, the Treble is Inverted, whilst the Tenor is used by similar motion.
    6. Stretto VI, the Alto is Inverted, whilst the Bass is used by similar motion. As an Episode is placed between these last two Stretti, the remark does not apply which was made in the instances of I with II and III with IV.
    7. Stretto VII. This is a complete Stretto, as all the voices take part in it.

The Episodes are of simple construction, being formed chiefly from fragments of the Subject and Counter-subject.

The great devices of this Fugue:

  1. The (Free) Inversion of the Subject, producing as it does a good workable Theme. (See Bar 42.)
  2. The capability of the Subject to take the Answer against it by Inversion at the distance of a minim (half note) (Bar 80).
  3. The capability of the Subject when Inverted to work with the Counter-subject, also Inverted (Bars 42, 50, 52, 54, 58).
  4. The capability of the Subject and Answer to work in Stretto at the distance of a minim.