Vom Himmel hoch, da komm ich her, BWV 700

For this piece, Bach arranged a cheerful Christmas chorale, with words and music written by Luther himself. The first two lines of the chorale paraphrase the words of the angel who brings the glad tidings to the shepherds: “I descend from heaven on high; I bring you wonderful new tidings”. It has been suggested that in Luther’s day this chorale was sung at the traditional Christmas play of the biblical nativity, where sometimes an angel came down on a rope. Bach does something similar at the beginning of this chorale arrangement. In the opening bars, it seems like he will use the chorale in a perfect fugue. The four parts come in one after another, from high to low, with the first line of the chorale melody. This is followed by a few pretend entrances, giving the impression that there are more than four parts, and the pedal eventually joins in after twenty bars. But then, as if the young Bach (it is an early work) had underestimated this ambitious intention, the piece continues with freer imitations and figurations of the chorale melody.
(source: AllofBach)