Canonic Variations on "Vom Himmel hoch da komm' ich her"
In June 1747, Bach was allowed to become a member of the "Correspondierde Societät der Muscialischen Wissenschaften" (Corresponding Society for the Musical Sciences).  There were 14 members when Bach joined.  The society studied and encouraged people in Leipzig to compose music.  To celebrate becoming a member, Bach gave to the society a version of the Canonic Variations and also a portrait of himself that had been painted by Elias Gottlob Haussmann.  In the portrait Bach is seen holding up a copy of another composition which uses a lot of canon.