Exposition, bars 1 to 9

It is a three-part fugue. The answer is a tonal answer and the order of the voices is soprano, alto, bass:

Exposition, bars 1 to 9

In bar 3, a free counterpoint accompanies the tonal answer. There are several motives:

• Motive 1a is the diminution of the last two notes of the theme.
• Motive 1b is the inversion and diminution of the last four notes of the theme.
• Motive 1b¹ is an extended version of motive 1b.
• Motive 1c is the diminution of the first notes of the answer.

Exposition, bars 1 to 9

Measures 5 and 6 prepare the entrance of the third voice, and new motives appear.

• The lower voice repeats motives 1b and 1a (inverted).
• The upper voice presents the new motives 2a and 2b.
• Motive 2b is an augmentation of motive 1a.
• Motive 2c is a variation of theme 2a.

Exposition, bars 1 to 9

The third voice enters in bar 7 to conclude the exposition.

• Motives 1 and 2 accompany the subject.
• The first note of the subject in bar 7 is harmonised as the seventh of the dominant chord of the dominant.
• The exposition ends in measure 9.

Subject, answer and motives

This image summarises the thematic material of this fugue: subject (S), answer (A) and motives.

• We have subdivided the subject and answer into several motives (S₁, S₂, A₁, A₁).
• Motif 3 will appear later in the fugue.

Measures 9 to 17

The first episode begins in measure 9.

• From bar 10 onwards, we find motives of the subject and the answer following the order S₂ A₁.
• If we look at the pattern, starting with the A₁ motive in bar 11, we see a subject that combines the first part of the answer with the second part of the subject, forming an ascending progression (B flat in bar 11, C in bar 13).
• The bass introduces the subject in measure 15.

Measures 9 to 17

The other voices reuse motives 1 and 2 and present motive 3 for the first time. We consider theme 2a² to be a variant of theme 2a.

Measures 9 to 17

Bach moves through the keys of F minor, A flat major and B flat major before returning to E flat major to introduce the subject (bar 15).

Measures 17 to 21

A new episode based on motives 3 and A₂ leads us with an ascending progression to the dominant of E flat major.

1. simplified march.
2. auxiliary chords are added.
3. realisation using motives 3 and A₂.

Measures 21 to 29

A final presentation of the subject by the soprano, followed by a coda, brings section A to a close.

Section B freely develops the thematic material and does not follow the contrapuntal structure of a fugue.

Measures 29 to 37

Between arpeggios, partial motives and the subject reappear.

• Measure 31: the subject, as an inner voice, leads us to B flat major.
• Measures 34 to 37: the B flat major passage is repeated and we return to E flat major.

Measures 37 to 41

Two partial motives of the subject lead to the presentation of the subject (bar 39), which begins in E-flat major but ends in A-flat major.

From now on, we are only going to point out the subject and the most important motifs.

Subject, answer and motives

The subjects presented in bars 31 to 39 show an ingenious use of subject and answer motives.

• Bar 31: S₁ and A₂ end a second higher.
• Bar 35: S₁ and S₂ end on the same note.
• Bar 39: A₁ and S₂ end a second lower.

Measures 41 to 47

A circle of fifths progression leads us to the presentation of the subject in C minor.

• Measure 41: the circle of fifths progression begins in A flat major and ends in F minor.
• Measure 43: the subject begins as the inner voice and ends as the upper voice.
• Measure 45: C minor is used as a second degree to modulate to B flat major.

Measures 47 to 55:

We begin in B flat major and move through G minor and F minor before returning to E flat major.

Measures 47 to 51:

• A descending progression based on the A₁ motive ends with S₂, taking us from B flat major to G minor.
• Measure 48, first beat: a clear cadence resolves to B flat major, but the upper voice immediately presents the dominant of G minor. Two harmonies in one beat? Polychords? Polytonality?
• Measure 49, first beat: we resolve in a similar way to the tonic, but the upper voice presents the dominant chord again.

Measures 51 to 55

• Measures 51 to 53: a descending progression with the motives A₂ and S₂ leads us to F.
• Measures 53 to 55: the progression is repeated and we arrive at E-flat major.

Measures 55 to 61

An ascending harmonic progression takes us from E flat major to A flat major.

• Measures 55 to 57: from E flat major to F minor.
• Measures 57 to 59: from F minor to G minor.
• Measures 59 to 61: from G minor to A flat major.

Measures 61 to 71

Subject and recapitulation.

• Measures 61 to 63: subject in E flat major and a slight variation in its final notes.
• Measures 63 to 67: recapitulation of section B, now with elements of the fugue (motive 3).
• Measures 67 to 71: the previous measures are repeated in B flat major.

Measures 71 to 77

Last bars of section B and beginning of section A.

• Measures 71 to 75: F minor acts as the second degree of E flat major, and a progression affirms this key.
• Measures 75 to 77: serve as the final bars of section B, but also introduce the subject that begins the repetition of the fugue.