After our last two miscellaneous preludes, today we move into a short section of catechism chorales with “Dies sind die heil’gen zehn Gebot,'” BWV 635. This is one of Martin Luther’s six catechism hymns, which explain and expand on crucial aspects of Christian faith. Roughly, each stanza presents one of the Ten Commandments. As you might guess, this makes a very long hymn – 12 verses in total! – but then, the Lutherans have always loved to sing. The historian Charles Burney tells the tale of a 1772 visit to Bremen in inimitable style:
I found the congregation singing a dismal melody, without the organ. When this was ended, the organist gave out a hymn-tune …
After hearing this tune … repeated ten or twelve times, I went to see the town, and returning to the cathedral two hours after, I still found the people singing all in unison, and as loud as they could, the same tune, to the same accompaniment. I went to the post office … [and] returned once more to this church, and, to my great astonishment, still found them, vocally and organically, performing the same ditty …
This may give some idea how necessary length is, in the musical performances of some parts of Germany.
The melody of “Dies sind die heil’gen zehn Gebot'” is one of the strangest of all chorales; Burney might well have found such a tune “dismal.” As a folk song, it dates to around 1200; in its present form it goes back to 1524. It has a strongly modal character, nominally Mixolydian (G major with F♮). But look what happens at the end:
There we were, happily bellowing along in G-Mixolydian, minding our own business, and definitely not coveting our neighbor’s ox, when all of a sudden that B♭ in the melody came out of nowhere. (This is probably a later addition; early published versions of the tune don’t seem to have it.) Because of that B♭, all of Bach’s settings lean heavily flatward at the end, making an already serious tune sound even more stern.
When Bach set this chorale, he loved to illustrate in music the idea of God’s law. The strictest way to represent the law is with a canon, or exact imitation, and this is what Bach does in BWV 678, from Clavierübung Part III. Similarly, in the astounding first movement of Cantata No. 77, he sets the tune – without text – as an augmentation canon between a trumpet in its very highest register and the bass in its lowest range.
Bach frequently embedded number symbolism into his settings of this chorale as well. In the small organ prelude, BWV 679, from Clavierübung III, he writes a fugue in which the subject covers exactly 10 semitones, and enters exactly ten times. In the opening movement of Cantata 77, the trumpet has ten entrances; and BWV 678 is the tenth chorale prelude in Clavierübung III.
It’s harder to discover instances of the number ten in the Orgelbüchlein prelude. Albert Schweitzer claims that there are ten entrances of the opening motive with exactly the same intervals. This seems to me like grasping at straws, since there are also fifteen other entries with slightly different intervals. Harvey Grace, on the other hand, complained that the piece was about “insistence, order, dogma – anything but statistics.” Here’s the opening:
The opening motive is a diminution of the first phrase of the tune. The rigid insistence on steady, unwavering eighth-note rhythm sets the mood; this prelude fairly wags its finger at you.
This motive is used both right-side up and in inversion, and it’s never for a moment absent until the very last bar. If you put words to it, you’d hear “These are the Holy Ten Commands” repeated incessantly throughout the whole piece. The point Bach makes here is that God’s commandments permeate everything. They run through the entire structure of the prelude, and, Bach suggests, inform all aspects of life. You might as well try to get away from them as give up oxygen for Lent.
Here’s a performance by Jacques Amade:
The Daily Bach: Blogging the Orgelbüchlein 
