Posthumous and unfinished work by J. S. Bach, orch. 1748–9, pubd. posthumously 1750, and designed to establish the possibilities of a simple subject in the various types of fugal and canonic writing.
It is not clear what medium was intended to be employed, or, indeed, whether actual perf. was in view. Modern edns. for pf., org., and versions for str. instr. and for orch. have appeared. Completions of the final fugue have been made by Donald Tovey and by Busoni in his Fantasia contrappuntistica.