Walther uses this well-known chorale as the theme for a fascinating set of 13 variations. Here's a brief description of each.
Variation 1: Manuals-only with some echo effects briefly in the second half
Variation 2: Manuals only featuring a continuous 16th note figuration in the right hand accompanied by 8th note leaps in the left hand. Enjoy the 16' Rankett I used here ;-)
Variation 3: Running 16th note figurations in the manuals decorate the theme appearing in the pedal line
Variation 4: This lengthy variation features some highly florid counterpoint in the manuals with the theme appearing in the pedal line
Variation 5: Similar to the previous variation, imitative counterpoint in the manuals, theme in pedal
Variation 6: Manuals only with frequent switches between two manuals
Variation 7: A type of Bicinium, theme in half notes in the right hand accompanied by continuous triplets in the left hand
Variation 8: In 12/8 meter, the theme appears in dotted half notes in the left hand, accompanied by steady 8th notes on a different manual in the right hand and dotted quarters in the pedal
Variation 9: A Trio for two separate manuals and pedal, which carries the theme
Variation 10: For two manuals and pedal. The theme appears in the pedal and in a highly ornamented version in the right hand. The left hand accompanies in 2-part counterpoint.
Variation 11: Manuals only with the theme in the soprano
Variation 12: Manuals only. I like the clever repeated cadences at the end of each phrase.
Variation 13: Manuals only (except for pedal on the final note), features some very fine writing by Walther. Theme in soprano