A chromatic fantasia is a specific type of fantasia originating in sixteenth-century and based on a chromatically descending tetrachord which arises naturally out of the dorian mode. Consequently the chromatic fantasia is almost invariably in D minor, even as late as Bach. This particular work, composed around 1723 and published 79 years later (with a revision after 1730), is in two sections and demands a very skilled performer. Fantasía 903a is a surviving earlier version of the work, possibly dating from before 1720.
