Thomas Braatz wrote (August 1, 2001):
BWV 107 - Specific details on the separate mvts.
Mvt. 1 Chorus and Instrumental Ensemble
Audus (1993) has an apt description of the opening of this mvt.: "The music appears to grow out the note B by successive, stepwise entries.
Romijn (1999) writing for the Leusink series says, "The instrumental opening loosely refers to the chorale melody, the chorale lines are woven into the musical structure in a beautiful way, the name Immanuel ('God with us') at the end of line being singled out for special treatment.
Finscher (1980) states that this mvt. "is set as a spacious choral with the decorated melody in the soprano line, the instrumental ritornello and the chorale are not thematically or stylistically linked, but simply follow one another, the ritronello performing the function of expressing the sentiments of sadness and consolation to which the words refer."
Dürr's explanation of this mvt. goes as follows: "The cantus firmus supported by a horn is also supported by the lower voices which have their own thematic material, although there are a few references hinting at the chorale in the other voices and in the orchestral parts. Rich in woodwinds (2 flutes and 2 Oboi d'amore), the flutes and strings (not cello/continuo) in several places create a kind of concertino. The oboi d'amore are sometimes part of this concertino, at other times they play the cantus firmus. The chorale is not presented directly one line at a time with short instrumental interludes in between, but rather appears as follows: 1) lines 1-2 (1st stollen), 2) lines 3-4 (2nd stollen), 3) lines 5, 6-8 (Abgesang). What happens in the choir is that the material used in the supporting voices (A,T,B) does not precede and prepare the entrance of the cantus firmus, but rather lags behind it, using a loose form of chordal structures that moves easily."
Mvt. 2 Bass Recitative
Due to the difficulties inherent in setting a choral verse as a recitative, normally a rather free form, Bach decides to avoid the danger posed by following the strict, formal structure of the chorale verse by using 2 Oboi d'amore which create a bridge between the gaps that would otherwise appear. He also extends both of the final lines with melismas on "Freuden" ("joys") and "retten" ("to save.") Another factor that loosens up the stirct structure is the arioso at the end which serves as a bridge to the next mvt. (Dürr and Finscher)
Mvt. 3 Bass Aria
Schweitzer: "The solo violin has a series of wild scale passages, the tempo of which Bach has placed beyond doubt by his marking of 'vivace.' Regarding "Auf ihn magst du es wagen.Du wirst mit ihm erjagen, was dir ist nütz und gut," ("Thou mayest venture on it with Him.thou wilt win with Him what is good for thee,") Bach was fascinated by the image and could not resist the temptation to illustrate it."
Finscher: "This mvt. and mvt. 6 are both in a major key. The orchestration, somewhat fuller, almost dance-like in its buoyancy, is in its inflection positively modern, almost in the galant manner. The middle stanzas are in minor, lightly scored, and they contrast with one another in accordance with their texts."
Dürr: "This and the following arias (4 in a row!) are in a basically 2-part rather than 3-part structure "
Mvt. 4 Tenor Aria
Dürr: "By using the bc only, Bach gives the voice more freedom of mvt."
Schweitzer: "This aria gives Bach the opportunity to depict the contortions of the body of the huge dragon."
Finscher: "This aria depicts Satan rising up and raging in a quasi-ostinato
continuo motif and wild coloratura."
Mvt. 5 Soprano Aria
Dürr: "This aria is closest in its thematic material to the original chorale. This already begins in the instrumental ritornello where the resemblance or embellishment of the chorale melody is apparent, but even more so when the solo voice enters. The final line of the chorale verse appears in its simplest at the conclusion of the aria."
Spitta: "The last line of the chorale appears completely unelaborated in its utter simplicity, as if the composer's creative fantasy once more returns to its source."
Mvt. 6 Tenor Aria
Heighes: "This tenor aria is in strong contrast to the first tenor aria. The unison flutes help to sustain a mood of happy assent to the will of God."
Mvt. 7 Chorale (Choir and Orchestra)
Audus: "This is set as a siciliano with orchestral interludes, which derive further impetus from a series of striking suspensions."
Dürr: "Once again Bach groups several chorale lines into one. The horn supports the soprano. The instrumental accompaniment, combining strings and winds, takes on an independent character and movement as a blossoming siciliano rhythm."
Finscher: "The extended instrumental siciliano recalls the end of the 5th stanza which, at the beginning, paraphrases the chorale melody, a highly effective 4-bar epilogue ending in the major. This appears to comment once again on the emotional progression from sadness to sure faith."