The last decade of Bach’s life had the feel of a musician’s retirement; he worked and taught as much as ever, but nonetheless found ways to shift his creativity away from regular duties as Cantor in Leipzig to projects of a more personally satisfying nature. These projects including The Art of Fugue and the compilation of the B Minor Mass. So it was natural that when regular duty asked for a Christmas Cantata in 1743, he responded with Cantata No. 191, an adaptation of the Gloria used in the B Minor Mass, originally written as early as 1733.
The Gloria of the B minor Mass had eight movements, which Bach condensed to three in Cantata No. 191 by keeping only the first, the last, and one of the middle movements. This maintained the overall feel of the original but broke the continuity of the text, which was restored by changing the text in the second and third movements to a Doxology. This linked the second and third movements together as a unit, separated them from the first, and closed off the work as a whole. But it challenged Bach to rework a new text into music originally built around different words.
This lively live performance of the opening movement is propelled by standing strings and Baroque winds:
The opening movement differs only in microscopic details from the B Minor Mass. It divides in sections that contrast to savor each line of the standard Gloria text. The first, (Gloria in excelsis Deo), is set as a celebration in strongly punctuated counterpoint that dances in pure joy.
The second line [1:50] (et in terra pax hominibus bonae voluntatis) steps off the edge. The tempo and time signature change. Dancing is balanced by quietly shifting elegance. The voices cadence [2:31]. An instrumental interlude cuts further along an edge to prepare a new fugue [2:58] about the pleasures of being ornate.
Twenty-one measures at the end of the duet for soprano and tenor in the pastoral second movement was eliminated from the corresponding place in the B-Minor Mass in order to better anticipate the burst of energy which opens the third movement. Strongly contrasting textures of quickly articulated syllables balanced against coloratura close a work that is a classic example of compositional process in late Bach.
Bach, even in false retirement and somewhat disgruntled, could still dazzle.