Our most familiar image of Bach is that of the cantor of the Thomaskirche in Leipzig. For 27 years, Bach was in charge of church music for Sundays and festival music for the four principal churches of Leipzig: the Thomaskirche, the Nicolaikirche, the Peterskirche, and the Neue Kirche. It was here that he composed many of his cantatas, his passions, which have since become famous throughout the musical world... But here he also composed his Six Motets.
These Motets are occasional compositions, composed for one-time events, four of them were for funerals. Only one of the motets can definitely be linked to a particular occasion: Der Geist hilft unser Schwachheit auf, which was composed for the funeral of Johann Heinrich Ernesti, the rector of the Leipzig Thomasschule, on 24 October 1729.
The motet Lobet den Herrn, alle Heiden is stylistically and formally rather different from the five others, and as a result Bachs authorship of the composition is still in doubt. The jubilant text of Singet dem Herrn ein neues Lied, in any case, does not suggest a funereal occasion. Bach researchers have suggested two possible occasions for the work: New Years Day 1727, or the birthday of Friedrich August, at that time the Elector of Saxony and King of Poland, on 12 May 1727. In particular, the texts referring to mortality in the central movement might be explained by Friedrich Augusts recent near-fatal illness. The Motet is written for two four-voiced choirs and consists of three movements, comparable to those of an instrumental concerto: the texts of the lively first and third movements are taken from Psalms 149 and 150. Both movements are veritable songs of rejoicing for two choirs. They flank the meditative second movement, like the Adagio of a concerto, organized around the central structure of a sustained chorale melody.
This motet is the composition that made such a deep impression on Mozart during the younger composers visit to the Leipzig Thomaskirche in 1789. The choir had only sung a few measures when Mozart rose from his seat, deeply moved. After a few more measures, he exclaimed "What is this?" Now it seemed as though he were listening with his entire soul! When the piece ended, he cried out, joyfully, "Now this is something that I can learn from!"