ABSTRACT
Perceiving the double presentation of a canon as two separate pieces was a structural weakness of the First Version. Indeed, in the Second Version of The Art of Fugue Bach removed this awkwardness, counting each canon as one piece rather than two. This resulted in a total number of 12 pieces rather than 14. Since the general guiding rule, requiring 14 pieces in total for the whole set, stayed intact, two more pieces were needed. These Bach provided in the last six pages (33-8) of the Autograph: two mirror fugues, the rst, marked in the Autograph as xiii, in four parts, and the second, marked as xiv, in three.1
