The movement begins with a fugue exposition in four voices. From the first bars, the motives m₁, m₂ and m₃ appear.

• m₁ : head of the subject, sixteenth, dotted eighth, sixteenth notes.
• m₂ : second part of the subject: triplets.
• m₃ : counterpoint to the answer: eighth notes.

Soloists exposition

The first exposition is played by the three soloists.

Measure
1	The principal violin begins with the subject.
3	The flute answers with a tonal response (the subject's initial fourth becomes a fifth in the response).
5	A four-bar passage using the triplet (m2) and the eighth note (m3) motives leads to the entrance of the third and fourth voices.
9	The third voice is the subject played by the left hand of the harpsichord.
11	The fourth voice is an answer in the right hand.
13	The exposition concludes by modulating to the key of the dominant (A major).

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Episode

The exposition is followed by an episode that develops the triplet (m₂) and eighth note (m₃) motives. A presentation of the subject interrupts the episode.

Measure
17	The harpsichord varies the triplet motive by using sixteenth note sextuplets.
19	The flute introduces the subject.
24	Flute and violin resume the dialogue using the triplet motive (m2).
29	The key of A major is affirmed and the orchestra (ripieno) enters.

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Second exposition

The orchestra (ripieno) enters with a three-part exposition. Subject in viola, answer in the violin and subject in the flute and solo violin:

First stretto

After an episode, the subject appears followed by an answer in stretto at bar 39:

Second stretto

After another episode, the viola subject is imitated in stretto by the violin in bar 65, followed by the cello, violone and harpsichord in bar 66:

Note that in the right hand of the harpsichord there is an incomplete imitation.

Harmonic analysis of the second stretto

• The answers appear on the subdominant (G major) in the second stretto.
• Bach achieves subdominant harmony by using IV degree secondary dominants.
• The third voice of the stretto, ends on a diminished G#. This chord is a vii/V of D major.

Measures 29 to 78

 

Exposition. Subject in the viola, answer in the violin and subject in the flute and soloist violin.

Episode using the triplet and eighth note motifs.

Stretto.

Episode with triplet motifs, eighth-notes and the sixteenth-notes of the harpsichord.

Subject in violoncello, violone and harpsichord and imitation by the flute.

Episode.

Subject in D major, imitated in stretto in G major, ending on a vii/V of D major.

Episode affirms the key of D major.

We end by playing the subject in D Major using the flute and solo violin.

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Section B presents a variant of the subject in the key of B minor:

Measures 79 to 128

Measure
79	Over a tonic pedal tone (B minor) and the triplet motive, the flute plays the theme variation (in red).
87	The violin and the viola interrupt with the subject.
89	The violin plays the theme variation.
97	Violin and viola play the subject and modulate to F# minor.
99	The harpsichord plays the theme variation.
106	Dialogue between the instruments using the triplet motif.
123	The violin and the flute present the subject at the conclusion of the passage.

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Measures 128 to 135

In a few bars we move through several keys: F# minor - B minor - E minor - A major. The subject is part of this ascending march.

Measures 136 to 148

• An ascending movement follows, this time diatonic in A major.
• A dialogue is established by means of the dotted sixteenth note of the subject and the triplet motive.
• The key of A major is affirmed in measure 148.

Listening to measures 128 to 148

 

F# minor

B minor

E minor

A major

Ascending progression affirms the A Major key.

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Measures 148 to 155

• The violin and the viola present the subject-based theme in A major (in red).
• The soloists, violoncello and violone, accompany with triplet and eighth note motifs.

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Measures 155 to 163

• Dialogue between the harpsichord using the triplet motive and the flute, violins and viola with the subject.
• We modulate from A major to B minor passing through E minor.

 

A major

E minor

B minor

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Measures 163 to 177

• The harpsichord plays the subject in canon form in the key of B minor.
• We end in the key of F# minor.

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Measures 177 to 193

• We start in F# minor and modulate to D major passing through E minor.
• A dialogue develops between harpsichord, orchestra and other soloists.
• We find the motifs m₁ and m₂ and the subject.

 

Fa# menor

Mi menor

Re mayor

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Measures 193 to 203

Measure
193 - 197	Dialogue between flute, solo violin, using the first notes of the theme.
	The harpsichord goes on with the triplets.
	We start in D major but modulate to F# minor.
198 - 203	The violone plays a dominant pedal tone.
	Flute and violin soloists interacting using the triplet motive.

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Measures 203 to 217

• Only the soloists play. The cello reinforces the bass.
• The flute and violin dialogue with the triplet motive.
• The F# minor dominant ( measure 203) leads us to E minor, until we reach a B minor dominant pedal tone in measure 217.

 

B minor

E minor

B minor's dominant pedal tone

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License

Measures 217 to 233

Measure
217	A B minor's dominant pedal tone...
220	... leads to triple stretto.
225	At the end of the B section, an ascending march affirms the key of B minor.

Constance Schoepflin (flute), Roxana Pavel Goldstein (violin), Matthew Ganong (harpsichord), Advent Chamber Orchestra (orchestra)
EFF Open Audio License