Bach: Prelude and Fugue No.15 in G major, BWV 860 Analysis



Bach Prelude and Fugue No.15 in G major BWV 860 Analysis 1


The Prelude is founded of the figures seen above.

Bars 1-11: Period I. Tonic Pedal (Bars 1-3), touches D major (Bar 5), A minor (Bar 6) and E minor (Bar 8), ending with a Perfect Cadence in the key of the Dominant, D).

Bars 11-19: Period II. Dominant Pedal (Bars 11-13). Gliding to C and D major in its early part, and at its conclusion firmly clenching the Tonic key.


Especially noticeable in the opening bars are the skips of the Octave in the Bass part. These are frequently employed throughout the Prelude, and impart great sprightliness to it.

Period I may be divided at Bar 5, where a new Melody is started in the Treble in the key of the Dominant. Period II may be more conveniently divided into short Phrases, (1) at Bar 12, (2) at Bar 13, (3) at Bar 14, (4) at Bar 15, (5) at Bar 16, the first two Phrases being in a descending Sequence, the last three in an ascending Sequence.



Bach Prelude and Fugue No.15 in G major BWV 860 Analysis 2




Bars 1-5: Subject in Treble [G Major].
Bars 5-9: Real Answer in Alto [D major].
Bars 5-6: Codetta in Treble.
Bars 6-8: Counter-subject in Treble.
Bars 9-11: Codetta.
Bars 11-15: Subject in Bass. Counter-subject in Alto [G major].
Bars 15-20: Episode I, modulating from G to C, and back to G.
Bars 20-24: Subject by Inversion in Alto. Counter-subject (incomplete) by Inversion in Bass [G major].
Bars 24-28: Answer by Inversion in Treble. Counter-subject by Inversion in Alto [D major].
Bars 28-31: Subject by Inversion in Bass. Counter-subject (incomplete) by Inversion in Treble [G major].


Bars 31-38: Episode II, modulating from G to E minor.
Bars 38-42: Subject in Treble [E minor].
Bars 40-42: Counter-subject in Alto.
Bars 42-43: Codetta.
Bars 43-46: Subject by Inversion in Alto. Counter-subject by Inversion in Treble [E minor].
Bars 46-51: Episode II, modulating from E minor to B minor.
Bars 51-54: Subject in Treble [B minor].
Bars 52-54: Stretto [B minor].
Bars 52-60: Episode IV, modulating from B minor to D Major.
Bars 60-62: Subject in Alto. Counter-subject absent [D major].
Bars 61-64: Stretto II (incomplete). Subject in Treble, on pedal A [D major].
Bars 64-69: Episode V.
Bars 69-73: Subject by Inversion in Bass. Counter-subject in Alto [G major].
Bars 73-77: Episode VI.
Bars 77-79: Subject by Inversion in Alto [G major].
Bars 78-79: Stretto III (complete). Subject by Inversion in Bass [G major].


Bars 79-82: Subject in Treble, accompanied in 3rds below by the first part of Subject in Alto [G major].
Bars 82-86: Coda, the last two bars of which are on Tonic pedal. [G major].


Exposition: Bars 1-15.
Counter-exposition: Bars 20-31.
Episodes: Six.
Stretti: Three.
Inversion: Several instances.
Coda: Bars 82-86.


  1. This Fugue has a “real” Answer, and would be called a “real” Fugue.
  2. The Counter-subject appears somewhat late – not until the second half of the second bar of the Answer.
  3. Free Inversion is applied to the Subject and Counter-subject.
  4. All the Episodes are formed from the new figure used in the Codetta (Bars 5-6), sometimes with the addition of a free part
    1. Episode I is in a descending sequence with an additional new counterpoint in the Treble.
    2. Episode II is also in a descending sequence. The figure employed in the Treble of Episode I is here given to the Bass, and the Bass of Episode I to the Treble. Ornamental scale passages are introduced in the Treble at Bars 34 and 37 and in the Bass at Bars 35 and 36, the Alto having a detached figure.
    3. Episode III contains notes of greater lengths in the Treble, and florid work in the two under parts.
    4. Episode IV. The first bar of the Codetta figure is inverted and used in 3rds with the Bass. Demisemiquavers (thirty-second notes) are also introduced. In Bar 56 the Alto enters in imitation at the 4th below.
    5. Episode V. Here the Bass has a detached figure, the upper parts being much the same as in Episode II.
    6. Episode VI is in two parts only, the vigorous scale passages being again introduced.