Chromatic fantasia

A chromatic fantasia is a specific type of fantasia (or fantasy or fancy) originating in 16th-century Europe. In its earliest form, it is based on a chromatically descending tetrachord which arises naturally out of the dorian mode. Consequently, the chromatic fantasia is almost invariably in D minor (D–E–F–G–A–B♭–C rather than D–E–F–G–A–B–C) even as late as Bach.