Canonic Variations on "Vom Himmel hoch da komm' ich her"
This variation has a new tune in the right hand (but some of its general shape comes from the chorale tune).  It is very lively (there are often demisemiquavers, especially near the end), and is very syncopated.  The bottom of the left hand plays the same tune in canon, but it only moves at half the speed of the upper part. This is called “augmentation”.  The top of the left hand meanwhile has a freer part.  The pedal has the chorale tune in long notes.  Three bars before the end we hear the BACH motif in the left hand.  These are the four notes that Bach often uses to represent his name.