The opening chorus is an ecstatic celebration of God having sent His Son to humankind. The scoring includes trumpets, timpani, flutes, oboes, strings, choir, and continuo. The first four bars are set in motion by a solo for the timpani; and then the rushing scales of the woodwinds and the strings and the fanfares in the brass take tumultuous hold in an adulation of glorification.
An evangelist, whose voice Bach employs to sing the recitatives, in due course announces the birth of Christ (Luke 2:7), which introduces the chorale on the sixth verse of Luther’s Gelobet seist du, Jesu Christ, already found in cantata 91, also at the First Day of Christmas. The chorale, sung by the soprano, is interspersed with commentary by the bass on the usual paradox of the aim of salvation by the mortal Christ for sorrowful humanity, and this is dutifully elaborated in the succeeding aria for bass, which, with its return of a solo trumpet, is also annunciatory in nature.
The text and music of the concluding chorale derive from Martin Luther’s exquisite Vom Himmel hoch, da komm ich her, which Bach makes even more moving, filling the heart with the release that comes in joy.
For years on end my wife and I would play this cantata every Christmas Day, and I remember particularly one spectacular morning of light in Kelowna, in the Okanagan valley of British Columbia, as the quiet of snows at the lip of the canyon by the house seemed to respond in welcome to the great grace of this music.
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This is an excerpt from On the Cantatas of J.S. Bach, Book Four: Advent, Christmas, New Year. All six volumes on all the Bach sacred cantatas can be found here, or at all other major international distributors, here.