Werk BWV 548

Prelude and Fugue in E minor, BWV 548 is a piece of organ music written by Johann Sebastian Bach sometime between 1727 and 1736,[1] during his time in Leipzig. The work is sometimes called "The Wedge" due to the chromatic outward motion of the fugue theme.[1] Unlike most other organ preludes and fugues of Bach, the autograph fair copy of the score survives,[2] though the handwriting changes twenty two measures into the fugue to the hand of Johann Peter Kellner,[3] a likely pupil and acquaintance of Bach who played an important role in the copying of his manuscripts. Because of the work's immense scope, it has been referred to as "a two-movement symphony" for the organ.[4]