After this four-three suspension is resolved in measure 27, the dominant seventh chord first passes through its fully diminished secondary leading-tone seventh chord over a dominant pedal in measure 28 and then another tonic pedal six-four chord in measure 29, which resolves back to the dominant seventh chord in a similar fashion as before. The resolution of the C, however, is delayed an additional measure and forms a four-three suspension when the dominant seventh chord reappears in measure 26. First, the dominant seventh chord passes through a tonic pedal six-four chord in measure 25.
_When the dominant seventh chord arrives in measure 24, a crescendo of tension builds poco a poco as its resolution is delayed until the climactic final measure. Again, the fully diminished leading-tone seventh chord of the tonic is borrowed from its parallel minor (C minor) however, in this instance, it is used as an embellishment and not for its dominant function. Namely, the fully diminished secondary leading-tone seventh chord of the dominant (preparing G from F-sharp below) and the fully diminished leading-tone seventh chord of the tonic in third inversion (preparing G from A-flat above). _After the subdominant seventh chord is tonicized by its secondary dominant seventh chord in measures 20 & 21, the forthcoming dominant pedal is further prepared by two successive fully diminished seventh chords in measures 22 & 23. 24-31), and an implied tonic prolongation over a tonic pedal (mm. 20-23), a dominant prolongation over a dominant pedal (mm. _ The coda is an elaborate sixteen-measure cadential gesture comprised of a predominant prolongation (mm. Phrases 2 (b) and 3 (b’) combine to form a parallel period. The phrase concludes with an imperfect authentic cadence in the tonic key (C major) and is essentially the conclusion of the prelude. Looking back at Phrase 2 (b), measures 16-19 (Sequence X) are an imitation of the model in measures 8-11. The fully diminished secondary leading-tone seventh chord of the tonic is borrowed from its parallel minor (C minor) for its dual tendency tones: ti (B), which resolves up to do (C), and le (A-flat), which resolves down to sol (G).
The first sub-phrase is a short descending seconds sequence embellished with fully diminished secondary leading-tone seventh chords that returns the tonal center to the tonic (C major) from its departure to the dominant (G major). _Phrase 3 (b’) is a regular eight-measure phrase divisible into two sub-phrases (mm. The phrase concludes with an imperfect authentic cadence in the dominant key (G major). Looking forward to Phrase 3 (b’), measures 8-11 (Sequence X) provide the model for the imitation in measures 16-19. Curiously, the end of the first sub-phrase overlaps with the beginning of the second in measure 8, and this asymmetry may ultimately account for the Schwencke measure. The first sub-phrase is a descending fifths sequence that shifts the tonal center from the tonic (C major) to its dominant (G major). _Phrase 2 (b) is an irregular seven-measure phrase divisible into two sub-phrases (mm. First, the tonic chord progresses to the supertonic seventh chord in third inversion next, the supertonic seventh chord progresses to the dominant seventh chord in first inversion and finally, the dominant seventh chord resolves back to the tonic chord in an imperfect authentic cadence. It serves as an introduction insofar as it presents the motive (the broken chord) and establishes the key (C major). _Phrase 1 (a) is a regular four-measure phrase. Of course, as a piece from the common practice period, chordal sevenths are treated as dissonances requiring careful approach and resolution. It is also noteable for the smoothness of its voice leading and the tension built throughout its lengthy coda, which accounts for nearly half the entire prelude.
_The famous prelude opening The Well-Tempered Clavier, Book I is both wonderfully classical in its harmonic richness and wonderfully modern in its repetitive simplicity.