section_path: Musical style/Four-part harmony
section_name: Four-part harmony
paragraph_text: Four-part harmony
  
  Four-part harmonies predate Bach, but he lived during a time when modal music in Western tradition was largely supplanted in favour of the tonal system. In this system a piece of music progresses from one chord to the next according to certain rules, each chord being characterised by four notes. The principles of four-part harmony are found not only in Bach's four-part choral music: he also prescribes it for instance for the figured bass accompaniment. The new system was at the core of Bach's style, and his compositions are to a large extent considered as laying down the rules for the evolving scheme that would dominate musical expression in the next centuries. Some examples of this characteristic of Bach's style and its influence:
  
  Bach's insistence on the tonal system and contribution to shaping it did not imply he was less at ease with the older modal system and the genres associated with it: more than his contemporaries (who had "moved on" to the tonal system without much exception), Bach often returned to the then-antiquated modi and genres. His Chromatic Fantasia and Fugue, emulating the chromatic fantasia genre as used by earlier composers such as Dowland and Sweelinck in D dorian mode (comparable to D minor in the tonal system), is an example of this.