Bach wrote four sets he called Clavier-übung, or keyboard practices. The first two and the last one contain some of his most famous harpsichord works now the province of pianists – the Six Partitas, The "Italian" Concerto and the "Goldberg" Variations. Clavier-übung III, known as the "German" Organ Mass, is far less often encountered.
Supposedly, Paul Jacobs' performance at Walt Disney Concert Hall on Sunday night will be its first ever performance in a Los Angeles concert hall. That is not easy to prove, given that Bach published his collection in 1739. Then again, not too many Los Angeles concert stages over the years have had organs, and none comparable to Disney's marvelous instrument.
The main reason that this collection, despite containing some of Bach's most brilliant and probing keyboard pieces, is so little known (even recordings outside of complete Bach organ sets aren't plentiful) is that the "German" Organ Mass is a peculiar miscellany. It contains the popular prelude and fugue, the massive "St. Anne," the prelude beginning the collection and the fugue, some two hours later, ending it.
In between come 21 chorale preludes, each a contrapuntal fantasy around a Lutheran hymn tune. No two are similar and the variety is dazzling, ranging from extensive investigations in the harmonic depth and complexity to flute-like little fugues. Then follow four duettos, or two-part inventions.
Bach had his reasons, and what they might be has given scholars work for centuries as they scrutinize inner liturgical meaning. Organists are fascinated by amazing music that permits creativity, especially in how the player will chose to color the chorale preludes and duets with different kinds of organ stops.
As for audiences, they get a chance to discover a feast of Bach that, with the exception of the "St. Anne," hasn't gotten out in the concert world much – or maybe, as in L.A., at all.