The Prelude and Fugue in C minor, BWV 873, is a keyboard composition written by Johann Sebastian Bach in 1738. It is the 4th prelude and fugue in Book II of The Well-Tempered Clavier.
The prelude is in the time signature of time. It is in the key of C minor. The Prelude is heavily ornamented with mordents and appoggiaturas.
The fugue is in time. It is also in C minor. Unlike its prelude, the fugue does not have much ornamentation.