Canonic Variations on "Vom Himmel hoch da komm' ich her"
In the last section, marked forte, the pedal part plays the chorale tune upside down.  At the very end, as the music rises to a climax, it repeats the last line of the chorale tune, finishing on the lowest pedal note: the bottom C.  The hands meanwhile play on the same manual.  There is a “stretto”: all the voices start the tune (or a version of the tune) quickly one after another.  At the very end we hear the BACH motif again.