Wim S. Ros
Het ORGEL 93 (1997), nr. 10, 6-19 [summary]
Bach planned 164 choral preludes in the manuscript of the Orgel-Büchlein. He completed 45 preludes (the two on Liebster Jesu, wir sind hier are counted as one). He notated 44 of them between 1713 and 1716, and the 45th in 1740. Breig and Löhlein say that the reason that Bach restricted the number of preludes has to do with the exemplaric identity of the preludes.
According to number symbolism Bach considers in 1716 to represent reconciliation: 44 (the number of the preludes) = 4 (cross, Adam) times 11 (sin), or 2 (God) times 22 (Psalm 22). In 1740 the central theme is the crucifixion: 45 = 19 (God and his commandments) + 7 (mercy, the seven words of the crucified Jesus) + 19. The 7 chorales in the middle are for the Holy Week and form a musical sermon on the significance of Jesus and his crucifixion. The first two chorales are the propositio, the three in the middle the explicatio and the two at the end the applicatio.
The current conception of the Orgel-Büchlein as an unfinished work and the assumption that there are only a few links between the chorales, are no longer valid. This has consequences for the playing of the chorales.
Specifically, one basic tempo might be chosen for the passion chorale preludes.