canon as "law". As also expressed in Luther's verses, the two voices of the canon have been seen as symbolising the new law of Christ and the old law of Moses, which it echoes. The pastoral quality in the organ writing for the upper voices at the opening has been interpreted as representing the serenity before the Fall of Man; it is followed by the disorder of sinful waywardness; and finally order is restored in the closing bars with the calm of salvation. The upper part and pedal engage in an elaborate and highly developed fantasia based on motifs introduced in the ritornello at the beginning of the chorale prelude. These motifs recur either in their original form or inverted. There are six motifs in the upper part: the three crotchets at beginning of bar 1 above the dotted minim in the second part of bar 1 above the six note quaver figure in the two halves of bar 3 above the phrase of three semiquavers and two pairs of "sighing" quavers in bar 5 above the semiquaver passagework in the second half of bar 5 above the semiquaver passage work in the second half of the second bar below (first heard in bar 13) and five in the bass: the three crotchets at the beginning of bar 4 above the two crotchets dropping by an octave at the beginning of bar 5 above the phrase in the second part of bar 5 above the three note scale in the second, third and fourth crotchets of bar 6 above the last three crotchets in bar 7 above. The writing for the two upper voices is similar to that for obligato instruments in a cantata: their musical material is independent of the chorale, The opening pedal G on the other hand can be heard as a foretaste of the repeated Gs in the cantus firmus. In between the cantus firmus is sung in canon at the octave on the second manual. The fifth and final entry of the cantus firmus is in the distant key of B major (G minor): it expresses the purity of the Kyrie eleison at the end of the first verse, which brings the prelude to a harmonious close:BWV 679 Dies sind die heil'gen zehn Gebot (These are the holy Ten Commandments) The lively gigue-like fughetta has several similarities to the larger chorale prelude: it is in