Cantata 21 was the last of Bach's pre-Weimar cantatas, and may have been written in 1713 as his audition for a position in Halle. Portions of the cantata (movements 2-6 and 9) may have been written for the funeral of Aemilie Marie Harress in October 1713. Bach likely used the work for an audition in Hamburg in 1720. The autograph score, however, contains the date 1714, and we know that Bach used Cantata 21 for the Third Sunday after Trinity that year in Weimar, although Bach wrote "per ogni tempo" (for anytime) on the score, and it's clear from the text that this cantata is indeed appropriate for any number of feasts in the church calendar. Bach also reworked the orchestration for a performance of the work in Leipzig (1723), though none of these changes affected the structure or form of the work.
Scholar Eric Chafe has written a detailed analysis of the entirety of Cantata 21 (Chafe, Ch. 3 of Analyzing Bach Cantatas [New York: Oxford University Press, 2000]). Many of the items below are taken from Chafe's analysis (and credit is given appropriately), which both for the sake of brevity and academic honesty, is not repeated here. For those interested in more detail, I direct you to Chafe's complete analysis.
The librettist is anonymous, although several scholars think Salomon Franck is the author of the text. Franck and Bach collaborated on a number of other cantatas, beginning in 1714. The text contains few actual Biblical quotes (most come in the final chorus), although there are numerous biblical allusions, referencing all four Gospels, numerous books from the Old Testament (including at least twenty different psalms), and the book of Revelation.
This cantata features one of the largest orchestras of Bach's cantatas prior to Easter 1715: oboe, three trumpets, timpani, bassoon, strings, continuo, and SATB choir. Cantata 21 is a two-part cantata composed of nine movements, summarized below. For those who might be studying the score, please note that in virtually every movement, Bach employs a partial signature.
There are numerous musical moments worth exploring in Cantata 21, but I will detail only a few. Cantata 21 begins with an instrumental prelude, which stands completely independently (both in musical and formal terms). This kind of prelude is common among Bach's earliest cantatas (Christoph Wolff, The World of the Bach Cantatas: Early Sacred Cantatas [New York: W.W. Norton, 1997]). With the sinfonia's slow tempo, interwoven sober melodic lines (first violin and oboe), slow walking bass line, c minor key, and frequent suspensions in the inner string parts, Bach establishes an appropriate mood for the opening chorus - "Ich hatte viel Bekümmernis" (I have greatly suffered). Further suffering is portrayed in the use of fully-diminished seventh chords on consecutive downbeats just a few measures from the end. The first is not all that surprising, as we heard the same chord just two beats earlier, and because it inflects the dominant key area. The second one, which instead points towards f minor (the subdominant area), is unexpected. Bach writes a fermata on each of these two chords, drawing our attention to them more closely, and as the motion stops moving forward temporarily, we sense the composer searching for musical direction... or is this an attempt to end our suffering (that suffering we know of, from the title and from the mood of the sinfonia). It is a ruse, however, as Bach draws the music back to c minor for the cadence shortly thereafter.
The first chorus has a two-part structure with a brief introduction. The introduction is a mere three chords, on which the choir states three times "Ich". Following this is the first fugue of the cantata, a slowly moving fugue in which the choir states "Ich hatte viel Bekümmernis" numerous times. A single adagio measure ends the suffering with the word "aber" (but), as the second portion of music begins. This is not a fugue, although there is a good deal of imitative writing. This quick-tempo second half focuses not on the people's suffering, but rather on finding comfort from the Lord. Despite maintaining the minor mode, this portion of the movement definitely sounds more hopeful, thanks in large part to the quicker tempo and some very long melismas (which give it spirit).
The third movement, an aria for solo soprano with oboe and continuo, is a trio sonata in texture (two melodic lines with continuo accompaniment). Set in c minor and a lilting 12/8 meter, the opening line speaks volumes in terms of the affect: "Seufzer, Tränen, Kummer, Not" (sigh, tears, grief, need). The lamenting feeling is further reinforced through the use of numerous non-chord tones, especially falling appoggiaturas, suspensions, because, as Mattheson points out (Chafe, p. 53), the movement has no contrasting B section (that is, it is not a da capo aria), we never leave the lamenting feeling behind.
Chafe finds the fourth movement (a tenor recitative) important because it is, in his opinion, the only moment in which "the believer voices feelings of isolation from and rejection by God" (p. 53). The agony of the believer is portrayed appropriately by Bach in the minor key, chromatic twists, weak cadences, and generally unsettled feeling. The suffering of the soul reaches its low point with the subsequent aria (movement 5), set in f minor; with four flats in the key, this is the lowest point harmonically. Most notable here is the middle section, where the tenor sings "Sturm und Wellen mich versehren" (storms and waves overwhelm me); here, the music becomes immediately faster, and the tenor turns to singing a repeating, undulating passage:
The next chorus presents a series of surprises. Bach begins the movement with a solo quartet (accompanied by continuo); their singing lasts only four measures, at which point the full choir enters. The choir's music is parallel, though not identical, jumping immediately to A-flat major instead of remaining in f minor as the soloists had done. An additional surprise occurs with a phrase extension of two majors, ruining the parallel structure. The choir then turns away from this homophonic, chorale-type setting, and begins a rapid fugal passage (not a complete fugue) which moves through two full diatonic circles of fifths, one chord at a time, beginning in m. 11 (where the fugue starts). This imitative passage comes to an abrupt end in m. 26 with a rhythmic unison statement "in mir?" (in me). Another fugal passage emerges, this one adagio and relatively short. The solo quartet returns again with another fugue, which, after an instrumental bridge, is repeated by the full choir. This second fugue is linked to the opening movement through the use of repeated notes in the theme. The chordal movement by fifths and changing textures create a sense of unrest, which is a fitting closing to the first half of the cantata which began with the words "Ich hatte viel Bekümmernis".
In the second part of the cantata "the believer's coming under the influence of Trost, the 'point at which faith and experience intersect', love, which gives confidence to faith, and joy, the 'feeling quality' of faith" (Chafe, p. 56). As we also see in the famous Cantata 140 (Wachet auf), Bach here employs a dialogue between Jesus Christ (bass) and the soul (soprano). It is tempting to point out the move to E-flat major as another Trinity reference; in the very least, the E-flat key for both the recitative and duet stands apart from the other movements of the cantata. It is, therefore, a real turning point in the cantata. It is also both a duet, because two solo voices join for this movement, and a trio sonata in terms of texture, because the two melodic parts (soprano and bass) are accompanied by the continuo alone, without other instrumental support. Finally, the movement is divided into three sections, according to tempo and meter: a moderate 4/4, quick 3/8, and another moderate 4/4. Thus, there is a constant emphasis on threes (three flats in the key, three formal sections, three parts in the score, and a section of triple meter).
The ninth movement, "Sei nun wieder zufrieden meine Seele", is the only minor-mode piece in the second half, and in that sense the movement looks back to the beginning of the cantata. It is a large fugue based on the chorale "Wer nur denlieben Gott lässt walten" (Georg Neumark). The fugue is written in solo soprano, solo alto, and solo bass vocal lines, while the chorale tune remains the sole property of the choral tenors. The choral altos, tenors, and basses (the choral sopranos now have the chorale melody) take over the fugue for the final half of the movement, at which point Bach inverts the fugue subject from a descending line to an ascending one. We get the sense at this point that the music is now looking forward more than backward, and in using ascending lines, Bach is reaching towards heaven. (The example below shows the original subject and its inversion together for convenience sake.)
The final movement begins with a stately, homophonic, chordal introduction. The return to C major and addition of trumpets and drums make for a majestic start. The three trumpets, along with numerous melodic triadic figures, suggests the Trinity, as is common in Bach's works. Chafe also speculates that there are other numerological things going on in this cantata, and in this movement in particular, especially in the fugue which follows. In particular, there are numerous groupings in seven (both in ascending/descending triadic figures and in the phrasing), which represents heaven or eternal life (p. 68). The joy of this final movement reinforces the idea of heaven - the ultimate source for of joy for all Christians - after the somber opening movement focused on mankind's suffering.
With the start of the text "Lob und Ehre und Preis und Gewalt", a permutation fugue begins. A permutation fugue occurs when the subject is followed by one or more counter subjects which are treated canonically, with some freedom. This varies from a standard fugue in which the subject is the main recurring material; counter subjects, when present, are not treated so strictly in imitation. The musical example below shows the opening measures of the fugue in the vocal bass line Initially, the fugue is introduced by SATB soloists, rather than the choral voices. The fugue subject is marked in red, while the counter subject (which begins immediately - and simultaneous with the tenor entrance) is marked by green.
The tenor solo enters as the bass reaches the end of "Ewigkeit". This second statement of the subject is a good example of a tonal answer in a fugue. A tonal answer sounds similar to the original subject, but individual intervals are changed. Notice the changes in the example below:
We aren't really aware that the change has taken place, but if Bach used a real answer, one in which all the intervals were identical to the original statement - even if the starting note is transposed - the result would be dramatically different:
Instead of returning to C major at the end of the second statement, we would continue further away from the original tonic, landing instead in D major.
Beyond the fugal exposition, there are numerous other obvious imitative snippets once the choral parts come in. There is a double exposition of the fugue in this movement, with the subject introduced in each of the four solo voices (BTAS) before entering in each of the choral voices (in the same order). The solo voices do not continue independently once the full choir has entered.
The final movement has elicited great praise from Bach scholars, who can provide a sense of the drama of the movement:
The concluding chorus is a veritable coup de thêatre. In a dazzling declamatory outburst Bach suffuses his canvas in a radiance of colour, unleashing three trumpets and timpani for their first and only appearance in the cantata. This hymn of praise is in the form of a prelude and fugue whose jubilant, even heroic character brings one of Bach's most powerful cantatas to a resonant concluding 'Alleluia!' (Nicholas Anderson, "Ich hatte viel Bekümmernis" in Oxford Composer Companions: Bach [New York: Oxford University Press, 1999], 232).
Then comes a beautiful oboe-accompanied aria for soprano, and then, what can be described as the emotional heart of the cantata, the aria "Bäche von gesalzen Zähren". I can only describe the empty, hopeless loneliness conveyed by this aria by comparing its emotional effect to Barber's Agnus Dei. Another big choral interlude introduces hope: Why do you mourn my soul...Trust in God and a recitative followed by a duet (in which an emotional turning point seems to be signaled by a change to triple time) between the soul and Jesus introduces the ideas of the Gospel reading. The outstanding chorus "Sei nun wieder zufrieden" that follows is worthy of special mention. Its chorale prelude form with soloists weaving in triple meter around "wer nun den lieben Gott lüsst walten" contains writing of astonishing accomplishment.