:
The descriptions below are based on the detailed analysis in , and . Variatio I The two part canon is derived from the first and last lines of the cantus firmus. Despite the "enigmatic" notation for the printed version in the canon, Bach's musical style gives the impression of simplicity, gracefulness and beauty: no disharmony disturbs the pervading mood of peacefulness. The descending scale with which it starts is similar to the accompanying figures in
Christe, du Lamm Gottes,
BWV 619, of the
Orgelbüchlein. The falling scales have been interpreted as representing Christ's descent from Heaven to Earth, a reference to the text of the last verse. The repetition in the text "glad tidings of great joy" (iines 2–3, verse 1) provides a similar repetition for the music in the canon. The involved semiquaver passages with octave imitations, along with the slowly progressing harmonies, create an effect of resonant and echoing solemnity. Bach avoids monotony and lack of pace by modulating into the minor, followed by a brief G-major passage in the third line of the cantus firmus. The graceful introductory ritornello is recapitulated before the last line of the pedal cantus firmus, played in the tenor register with an 8' stop.
Variatio II The two part canon is based on the first and second lines of the cantus firmus. The compact imitative passagework follows the same scheme as Variatio I, but now with the canon at the fifth. Again the antiquated "puzzle" notation for the canon in the printed version belies the modern "natural" style, with pleasant writing and graceful slurs. The imitation follows a different pattern, less expansive with a shorter scale, the two distinct motifs answering in turn. With 23 bars in Variatio II compared to 18 in Variatio I, there is far more tonal variety, e.g. the minor modulation in bar 3. The secondary motive emerges from semiquaver figures on parallel thirds: beginning with bar 9, these develop into a climax at the start of bar 16 in the cantus firmus. The articulation of both the print and autograph versions give a calmer impression of the semiquavers in Variatio II than in Variatio I. From the last quaver of bar 4,
suspensions start to appear in Variatio II; further on, Bach's suspensions in the descending scales also hint at the beginning of Variatio I. As in Variatio I, there is a recapitulation of the opening ritornello—but now in syncopation with faster note values—before the last line of the cantus firmus, which is it at the same registration. The spirited rising scales above the closing pedal point are in contrast with the falling
arpeggios at the end of Variatio I. The ascending scales at the
coda of Variatio II have been interpreted as departing angels or the rising up of the soul (again a reference to the last verse of the text).
Variatio III ,
Sophienkirche, Dresden Variatio III is a longer composition lasting 27 bars. With the lower tenor and bass voices of the canons functioning as an accompaniment, the tenor entry is again delayed by two
crotchets. The melody in the alto is marked
cantabile in both the printed and autograph versions, with the soprano cantus firmus starting in even
minims on the
upbeat of bar 4. The canons themselves take the form of an
ostinato ritornello derived from the first line of the cantus firmus with interludes when the cantus firmus recurs. The two canons framing Variatio II and III are similar, the suspensions developing in the same way. In contrast the musical material in the cantabile passagework contains a remarkable range of expressive figures typical of the modern
galante style, with elaborate ornamentation,
melismatic episodes and occasional dissonant
appoggiaturas, resembling the solo part in an
aria. It also has similarities with the figurations in the solo line of the slow movement of the F minor harpsichord concerto,
BWV 1056. Amongst the notable ornamentation are the "sighing" suspensions and the syncopated
anapaests (played rapidly on the beat). The
cantabile melody was the most significant difference between the printed and manuscript version. Bach's practice was freely to extemporise on ornamentation, so that no performance was the same. From all the versions of the second line of the chorale, the musical intensity increased, with shorter and more frequent motives: the most intense dissonance occurs at bar 19, coloured with a winding
chromaticism. Similarly to Variatio II, there is a modulation to the
subdominant at bar 26: in the
pedal point, the rising figures of the cantabile melody contrast with the falling motives in the canon. In bar 19, the
chromaticism of the two canonic parts evokes the dragging of the cross (another example of musical iconography); the tensions of this episode are gradually resolved as the variation comes to a peaceful and harmonious close. In Variatio III, the third engraving of the printed text of
BWV 769, focuses on what he calls "the most modern of the set". The canon at the
seventh is scored in regular quavers with the voices in the tenor (lower manual) and the bass (pedal). The "enigmatic" notation in the printed version simplifies the score, so that the
cantabile part in the alto voice is easier to read. In this way Bach contrasts his antiquated way of notation with his modern style of writing. The upper manuals play the alto voice with the marking
Cantabile, while the soprano voice plays the cantus firmus in plain
minims. The lower voices in the canon, mostly play in intervals of thirds and sixths. Yearsley describes Bach's
galante style—characteristic of the alto melody—as full of musical motives containing "spontaneous and unpredictable ornamentation". When simplified by the ornamentation, the basic notes in the "skeleton" are harmonious: it is the different ornaments—be they suspensions, trills or
appoggiaturas—that cause disharmonies and create the expressive qualities of Bach's style. The musical theorist Scheibe, formerly a student of Bach, referred to this modern musical style as
delicate Sachen ("delicate things"). In the case of Variatio III, particularly Bach's ornamentation at the close of bars 26–27, Yearsley describes the new style as "marking the apogee of this natural elegance".
Variatio IV :
C.J. Hammer, c.1850 Variatio IV is an
augmentation canon in the soprano and bass manuals. It places far greater demands on the compositional technique than the earlier 4-part Variatio III. The middle alto voice in Variatio IV now plays as an accompaniment, producing a remarkable motivic dialogue between the bass
Comes canon.
Variatio V , 1714,
Freiberg Cathedral In this variation, the canon is the melody of the chorale itself. It has three sections, the first and second further subdivided in two, building up to a majestic and complex climax in the final bars of the third section. In the first section, the two manual parts play the chorale line by line in inverted canon over a walking bass
continuo stamped out in the pedal, first at an interval of sixth and then a third. In the second and third sections, the pedal part returns to the smooth lines of the cantus firmus. == Organ registration ==