Listen to the Prelude: https://youtu.be/1zNEZRHS0b4
Originally written for the Lute, this Dances Suite from J-S Bach includes the 6 usual dances of these Baroque forms: Prelude and Fugato, Allemande, Courante, Saraband, Bourrée and Jig.
Prelude:
It lasts 16 measures until the Fugato begins. It is written in a 4 binary times measure and may be played with a little rubato, like most Preludes (with a relatively free tempo).
Measures 1 to 4 are based on the melodic sequence pattern of the 2 first measures. Originally played on the E- tonic chord on the 2nd and 3rd beats of the 1st measure, this motif is then transposed on the A- and D#° chords. It consists in a downward motif from the 3rd to the root with a passing tone and chromatic approach notes. This sequence is modified on the last beat of the 2nd measure.
On the 1st beat of measure 3, this introductory motif appears again. Measure 4 is almost the repetition of the 1st measure an octave lower. This time the pattern goes from the dominant to the dominant. Last beat of measure 4 and first of 5 are a V – I conclusive progression (root to root: the bass only playing the dominant and tonic).
Measures 5 to 10:
Measure 5 is a 16th notes downward embellishment of the tonic chord tones with passing and double approach notes. From measure 7 to 9, there is a sort of harmonic sequence since chords are C#-7b5 F#7 and B- E7. In this sequence alternate an eight motif based on the introductory pattern and plated chords played on a French Overture rhythm. The soprano of each plated chord is a 7th raised degree of the key of the moment. Measure 6 sounds in the tonic key, 7 and 8 in the B minor key (dominant key) and measure 9 in the A minor key (subdominant).
Last beat of measure 9 is a downward natural scale of A minor played with a 16th notes rhythm. In measure 10, the soprano of the plated chords is now on the 7th of the E7 chord, the bass playing the 1st inversion of it. As the soprano plays the 7th of the E7 chord, it can’t resolve on a natural C (which would make A-). That’s why there is a AM chord on the 3rd beat with the delayed embellished of D on the soprano.
Last beat of measure 10 consists in an upward A melodic minor scale from the dominant (E) to the dominant (a dominant E7 chord from root to root with passing tones).
Measures 11 to 16:
After this E7 chord is a A- plated chord. On the 2nd beat there is a Neapolitan 6th, a first inversion of the FM chord (bIIM) with the soprano playing the root (F). This chord is a way to come back to the tonic key: it is both a VIM chord of the A minor natural key and the bIIM of the tonic key. As it is the case each time the Neapolitan 6th is used, the soprano plays the usual downward motion: F on the FM chord, the tonic E on a A- chord and D# on the dominant chord (a flat 2nd degree, the tonic, and a raised 7th degree). This process announces the end of the Prelude.
Note that measures 11 and 12 use a stepwise bass. In measure 12 is played the A7 chord (the bass being a delayed 7th), degree IV of the E melodic minor key. In measure 13, the soprano plays a dominant pedal over a dominant and a tonic chord. On the first beat of measure 14 there is a short modulation to the dominant key again with the chords F#7 (with a delayed 7th in the bass) and B-. 3rd and 4th beats of measure 14 modulate to the A minor key. On the 2nd beat note the downward natural minor scale of B from tonic to tonic played in a 16th notes rhythm.
In measure 15 the bass plays a dominant pedal. Over this bass are played the tonic chord, a F#M chord (V/V), the dominant chord, the tonic chord and measure 16 is a pause on the dominant chord.
So this Prelude is mainly based on the introductory 8th notes motif, 16th notes embellishment (stepwise scales), plated chords with a French Overture rhythm and harmonic sequences with modulations to neighbor keys. Measures 11 (with the Neapolitan 6th) and 15 (with the dominant pedal) may be played crescendo.
Fugato:
It goes from measures 15 to 74 and is now written in a 3/8 ternary measure. A great part of it is based on several Canons between 2 melodic lines (bass and soprano). Those Canons use a 2 measures motif which is roughly a downward motion from the dominant to the tonic. Note the similarity between the introductory pattern of the Prelude and the first measure of the motif of the Canon.
The first measure of it is made of quarter notes whereas the 2nd uses 8th notes, so that the 2 lines don’t follow the same rhythm when they are played together. The motif is first played by the soprano, the bass beginning one measure later and a 5th lower.
Where are the Canons and the harmonic sequences?
From measures 17 to 22 is a first canon. The Canon itself is based on a harmonic sequence: B7 E-, A- D7, GM CM (17 to 21).
From measures 23 to 28 is a 2nd Canon which is almost the inversion of the first: the bottom line playing the top line of the previous Canon an octave lower. This time the first line to play the motif is the bass, the soprano beginning in measure 24 (and so it sounds an upper 4th). Note that on the last beat of measure 23 the bass plays a E instead of a F# to fit with the tonic chord. From 24 to 28, the soprano line uses a downward chromatic motion: D#, D, C#, C, B.
From 29 to 34 is a 3rd Canon. The “soprano” or intermediate line begins to play it first. The bass plays it a 5th lower with a one measure time lag. This Canon is also based on a harmonic sequence: F#7 B7, E- A7 (D major key) and D7 GM. In measure 29, the bass (or intermediate line) plays a fake beginning of the Canon.
From 35 to 38 there is a harmonic sequence in the E minor key: GM E-, AM F#-7b5, B7 GM and CM A-. In measure 34 the last note of the bass doesn’t fit to the Canon pattern: it’s a A instead of a D. This clearly shows that it’s a guitar transcription, since the lowest pitch available on this instrument is the first E below the bass clef.
From measure 40 to 42, a 4th Canon is stopped in a short time. This one is the same as in measures 17 to 19.
Measures 42 to 44 use A- and E7 and sound in the A minor key (subdominant key). Note rhythmic pedal of the dominant of the moment E in the soprano.
Measures 45 to 54 sound in the G major key (the relative key of E minor). Note that measures 45 to 47 are like 20 to 22. There is a conclusive V – I progression in this key in measures 53 and 54. Note the anticipation of the tonic by the soprano at the end of measure 53. Before this progression, the 2 lines use the same rhythm. It can be also noted that in measures 48 and 49, the bass plays the previous soprano, and the soprano plays the previous bass.
From 54 to 57, we can hear a last Canon in which the soprano begins first and the 2 lines are separated by one measure and a 5th interval. Once again, this one is based on a harmonic sequence: E- A7 (D major key) and D7 GM (relative key). Note that measures 54 and 55 are the same as the same as 32 and 33 an octave upper. Moreover, measures 54 to 56 are like 25 to 27. In measure 58 the A- chord brings back the tonic key since it is both a degree II of the G major key and IV of the E minor key.
61 to 64 recall a little 42 to 44. It sounds in the A minor subdominant key. Chords alternate between the dominant E7 and the tonic A-. Measure 60 recalls measure 31.
64 to 68 are made of an harmonic sequence FM B7 (back to the tonic key passing through a Neapolitan 6th), E7 A- (subdominant key) and D7 GM (relative key). The bass plays a subdominant pedal in measures 64 and 65.
69 and 70 also consist in a harmonic sequence (GM E- and A- F#-). On this sequence, from measure 69 to 72, note the nice chromatic upward motion from the dominant to the tonic played by the soprano. In measure 72, the bass also plays a stepwise motion from the dominant to the tonic but it’s going downward, so the 2 lines follow an opposite motion.
To conclude this Fugato is entirely based on the 2 first measures of the Canon. Unity is provided by some “hidden repetitions” of the Canon. Moreover, there isn’t a single measure which doesn’t use a part of the original motif. However variety is brought by modulations, chromatic lines, various registers, fake beginnings of Canons and a conclusive progression in the relative G major key (measure 55).