Bach: Prelude and Fugue No.20 in A minor, BWV 865 Analysis

Analysis

Prelude

Bach Prelude and Fugue No.20 in A minor BWV 865 Analysis 1

SUMMARY:

Bars 1-13: Period I. Starting in the A minor, it moves to the Dominant minor (Bars 5-7) before arriving arriving at the Relative Major by descending sequence. Ending with a Perfect Cadence in the Relative Major, C.

Bars 13-22: Period II. Modulatory (touches C major, G minor, and D minor) to Bar 20, the gently curving round to the Tonic.

Bars 22-28: Period III. Starting with the Theme (varied) in the Tonic key. Tonic Pedal and Coda that firmly grasps the Tonic key (Bars 26-28).

REMARKS:

This Prelude is constructed upon the Theme used in the Treble, the three component figures of which appear in Bar 1.

The Periods are capable of Subdivision. Period I may be divided into three sections at Bars 4 and 8. Period II into two section at Bar 20, and Period III into tow sections at Bar 26, where the Coda begins.

Fugue

Bach Prelude and Fugue No.20 in A minor BWV 865 Analysis 2

 

ANALYSIS:

ENUNCIATION SECTION:

Bars 1-4: Subject in Alto [A minor].
Bars 4-7: Real Answer in Treble [E minor].
Bars 7-8: Codetta.
Bars 8-11: Subject in Bass [A minor].
Bars 11-14: Answer in Tenor [E minor].

MODULATORY SECTION:

Bars 14-17: Subject by Inversion in Treble [G major].
Bars 17-18: Subject (first part) by Inversion in Alto [G major].
Bars 18-20: Subject by Inversion in Tenor [G major].
Bars 21-23: Subject by Inversion in Bass [D major].
Bars 24-26: Subject by Inversion in Alto [A minor].
Bars 27-30: Subject in Treble in Stretto with Tenor [A minor].
Bars 28-31: Subject in Tenor in Stretto with Treble [A minor].
Bars 31-34: Answer in Alto in Stretto with Bass [E minor].
Bars 32-25: Answer in Bass in Stretto with Alto [E minor].
Bars 36-39: Subject in Tenor in Stretto with Alto [A minor].
Bars 37-40: Subject in Alto in Stretto with Tenor [A minor].
Bars 39-43: Episode I (usually late for its first appearance), modulating from A minor to C major.
Bars 43-46: Subject in Treble in Stretto with Bass [C major].
Bars 43-46: Subject in Bass in Stretto with Treble [C major].
Bars 45-57: Subject (second part) in Tenor [C major].
Bars 46-48: Subject (second part) in Alto [C major].
Bars 48-51: Answer by Inversion in in Alto in Stretto with Tenor [D minor].
Bars 49-52: Answer by Inversion in Tenor in Stretto with Alto, and Codetta [D minor].
Bars 53-56: Subject in Bass in Stretto with Treble [G major].
Bars 53-56: Subject in Treble in Stretto with Bass, and Codetta [G major].
Bars 57-60: Subject by Inversion in Treble in Stretto with Alto [A minor].
Bars 58-62: Subject by Inversion in Alto in Stretto with Treble, and Codetta [A minor].
Bars 62-63: Answer by Inversion in Bass in Stretto with Tenor [A minor].
Bars 62-63: Answer by Inversion in Tenor in Stretto with Bass [A minor].
Bars 64-67: Subject in Bass in Stretto with Tenor [D minor].
Bars 65-68: Answer in Tenor in Stretto with Bass [A minor].
Bars 67-70: Answer by Inversion in Treble in Stretto with Alto [A minor].
Bars 68-70: Subject by Inversion in Alto in Stretto with Treble [D minor].
Bars 71-73: Episode II, modulating from D minor to F major.
Bars 73-75: Subject by Inversion in Bass in Stretto with Alto [F major].
Bars 73-76: Subject by Inversion in Alto in Stretto with Bass [F major].
Bars 76-77: Answer by Inversion in Tenor in Stretto with Alto and Treble [C major].
Bars 77-78: Subject in Alto in Stretto with Tenor and Treble [D minor].
Bars 77-78: Subject in Treble in Stretto with Tenor and Alto [D minor].
Bar 79: Codetta and Pause.
Bars 80-82: Subject in Alto in Stretto with Treble [A minor].
Bars 81-82: Answer in Treble in Stretto with Alto [E major].
Bars 83-86: Tonic Pedal. Three upper parts in Stretto [A major].
Bars 86-87: Coda and continuation of Tonic Pedal. Close on Tonic Major [A major].

SUMMARY:

Exposition: Bars 1-14.
Counter-exposition: None.
Counter-subject: None.
Episodes: Two.
Owing to the structure of the Subject, special interest is given to the Fugue by the manner in which the quotations of it constantly overlap in a kind of Canonic Stretto (See Analysis).
Inversion: Many instances.
Pedal: Three. (1) Dominant (Bars 60-62). (2) On the Dominant of the relative major (Bars 76-77). (3) On the Tonic (Bars 83-87).

REMARKS:

  1. This Fugue has a “real” Answer and would be styled as a “real” Fugue.
  2. The devices of Inversion and Canonical Imitation abound in this Fugue to such an extent as to give it a special character.
  3. Episode I is constructed upon the Subject, but Episode II of new material.
  4. This Fugue has three short Pedal points. The first of the Dominant (E), the Second on the Dominant of the Relative Major (G), and the third on the Tonic (A).

The latter part of this Fugue is somewhat irregular in form fragments of the Subject being introduced in the Subdominant minor, D (Bars 83-86), in order to suggest the major conclusion which is about to follow.