Scholars believe that this cantata, as well as BWV 120b (of which only the text survived) and BWV 120, are all adaptations of a lost cantata from Bach’s Köthen period. 120a is believed to date from 1729, composed for the wedding of an unknown couple. As you can see in the attached BGA score, many of its movements survived only as fragments either from parts or from a partial manuscript score which starts towards the end of movement 4.
Thanks to its close connection with BWV 120, and also to the fact that Bach reused movement 4 to open Cantata 29, it was possible to reconstruct 120a very satisfactorily.
The anonymous librettist wrote the full text for movements 1, 3, 6 and 7. For movement 2, they wrote recitatives around a short quote from a hymn by Martin Rinckart from 1636. Movement 5 is an original recitative closed with a response from Luther’s Litany. The text for the closing chorale (number 8) is stanzas 4 & 5 of a poem by Joachim Neander of 1680.
Like most wedding cantatas, 120a is structured in two parts – movements 1 through 3 to be performed before the ceremony, and from 4 onwards, after it. The opening movement is a majestic choral piece, scored (going by the surviving score of BWV 120) for 3 trumpets, timpani, oboes, strings and continuo. Notably, a later revision of this movement found its final home in the Credo of the Mass in B minor (“Et expecto”). The scale of this movement, and indeed of the whole cantata, hints at the fact that the bridal couple were probably prominent personalities.
After the grand opening, the recitative that follows is split into two sections, first one for the bass and second one for the tenor, with a choral interpolation between them on the Rinckart text.
Movement 3 is reconstructed from the 4th one in BWV 120. It’s a soprano aria accompanied by full string orchestra and a concertante violin. This music has its origin on the slow movement of the Sonata No. 6 for violin and harpsichord, BWV 1019a, which dates from a couple of years earlier.
After the wedding ritual and the sermon, the cantata resumes with another grand scale movement, this time a Sinfonia, which Bach also used later in Cantata 29 with some changes in orchestration. The piece is a reformulation of the Prelude of the Partita No. 3 for solo violin, BWV 1006, with the solo line given to the organ and addition of string orchestra accompaniment.
The Sinfonia is followed by a recitative for the tenor asking for blessings for the newly wedded couple, which is closed with a choral intervention on text and melody from the Lutheran Litany.
Movement 6 is also present in BWV 120, there as the opening movement. Fortunately, in this case we have both scores, so we can compare the two versions without the need for any reconstructions. The orchestration is the same in both (2 oboes d’amore, strings and continuo), but here Bach adds a voice, making it a duet (symbolizing the couple), changes the vocal lines significantly, and incorporates some structural differences to better serve the text, including a full da-capo section.
A bass recitative, in which the text addresses the couple directly in second person (perhaps impersonating the pastor?), leads to the 2-stanza closing chorale, on the text and melody of Neander’s “Lobe den Herren”, which Bach had also used extensively in Cantata 137. Bach adds the trumpets and timpani to the second stanza for an emphatic closing.
