You know that a piece of music is popular when you hear it being played while you're shopping in Argos. Bach's first Schübler Chorale for organ, Wachet auf, ruft uns die Stimme ("Wake, Awake, a Voice is Calling") BWV645, is one such piece. It sounds festive and seems to have become associated with Christmas. It is also blessed with one of Bach's best tunes, which positively skips along. Against this tune appears the noble chorale melody, which is a thing of beauty in itself. Beneath both runs a bass line which has a far from uninteresting character of its own. It's a winning combination. Like all the other Schübler Chorales, it's an arrangement by the composer of a movement from one of his cantatas, here from BWV140 (beginning at 14.39). There the tune was played by the violins and violas, here it's played by the right hand. There the chorale was sung by unison tenors (or a solo tenor), here by the organist's left hand. There the bass was played by the continuo, here by the organist's feet. The transformation could not sound more natural.
There are five more Schübler Chorales, not that you hear them with anything like the frequency of Wachet auf. Is that for a good reason? Are the others less special?
I think the answer would have to be 'yes' - with one exception. Though far from festive, so never likely to be piped to Christmas shoppers, the fourth Schübler Chorale is just as wonderful as its famous companion. Meine Seele erhebt den Herren (My soul doth magnify the Lord) BWV648 is an inward looking piece, with the bass (on the pedal) announcing a mysterious chromatic theme which the alto and tenor of the organ (the left hand) take up and sing in duet. Against them the phrases of the chorale tune appear in the soprano (right hand). The effect is magical. It's an arrangement of a splendid duet for alto and tenor from Cantata 10 (a movement called He remembers His mercy), where the chorale was given to oboes and trumpet (11.37 into the video). This is one of my favourite Bach pieces and should be played more often (as should the cantata).
What then of the rest?
Wo soll ich fliehen hin (Whither shall I flee?) BWV646 certainly has least going for it, being pleasant but rather ordinary (by Bach's standards). The hands develop a little figure that, aptly, runs hither and thither while the pedal plays the chorale. The cantata it was presumably taken from has not survived. (It doesn't come from Cantata 5, which is based on the same chorale melody.)
Wer nur den lieben Gott lässt walten (Who allows God alone to rule him) BWV647 is better and has a beautiful chorale melody, which is played on the pedal. Above it unfolds a three-part invention shared between the hands. This is transcribed from a charming soprano-alto duet in Cantata 93 (beginning at 11.00), where strings play the chorale.
I'm even fonder of Ach bleib bei uns, Herr Jesu Christ (Lord Jesus Christ, with us abide) BWV649. This is as festive in spirit as Wachet auf. The right hand has the chorale with the left-hand playing the delightfully catchy figurative line that makes the piece such a pleasure to hear. The pedal provides an unexceptional bass. The chorale is arrangement from a soprano aria in Cantata 6, where the catchy tune is played by a cello and the soprano sings the chorale.
Just as delightful is the final Schübler Chorale Kommst du nun, Jesu, vom Himmel herunter
(Come thou, Jesu, from heaven to earth) BWV650. The chorale tune, played here on the pedal, will be recognisable to lovers of Anglican hymns as Praise to the Lord, the Almighty. The soprano has a lively and tuneful theme, which may represent the hovering of an angel, and the left hand provides a bass to accompany it. This is an arrangement of a lovely alto chorale from Cantata 137 (3.26 in) where the angelic theme is played by a solo violin.
There's very little in this set that isn't wonderful, and the closing pair come close to being as wonderful as Wachet auf and Meine Seele erhebt den Herren.