J.S. Bach's occasional canon 'BWV1073' and "stacked" canonic procedure in the eighteenth century

Bach's life-long interest in canonic composition is manifest not only in the large-scale works devoted to exploring various contrapuntal techniques, but also in a number of short occasional works of a generally theoretical nature written throughout his life and usually placed in albums dedicated to students or friends. Canons of this kind were often notated in enigmatic fashion and their solution provided intellectual enjoyment to the dedicatees. Christoph Wolff suggests that Bach derived much pleasure from writing pieces in this genre and in solving similar puzzle canons by others. Wolff also suggests that Bach's occasional canons could "chjallenge his visitors with simple-looking yet complex vignettes of musical logic". Some eight occasional canons survive, and it is very likely that many more are lost.