Prelude and Fugue in C minor, BWV 847, form the second pair of works in Part 1 of the Well-Tempered Clavier, a collection of preludes and fugues for keyboard instruments by Johann Sebastian Bach.

A comparison with the Prelude and Fugue in C major at the beginning of the Well-Tempered Clavier reveals that the two preludes are very similar, but the two fugues are structured very differently. The prelude in C minor contains 38 4/4 bars. It also begins with a series of chords written out as semiquaver figures and surrounded by alternating notes. The movement is in two voices here, but homophonic. As in the C major prelude, there is an eight-bar pedal point on G from bar 21. The following section is characterized by several tempo changes, beginning with Presto. This presumably refers to a toccata-like free tempo, quasi improvisational. Bar 34 is marked Adagio, which calls for a recitative-like playing style with a variable tempo. The last four bars are to be played Allegro, returning to the opening tempo.

An early version is preserved in the Clavier-Büchlein for Wilhelm Friedemann Bach.

The fugue in C minor is in three parts and consists of 31 bars. In contrast to the C major fugue, it contains no strettos, but numerous interludes, the first before the end of the exposition, before the theme appears in the bass voice for the first time in bar 7. The complete lack of strettos and the numerous sixteenth-note runs lend the piece a playful and songlike character.[2] The conclusion of the fugue is designed as a dramatic climax: after the penultimate appearance of the theme in the bass, the flow of voices is abruptly interrupted by a short general pause in bar 28. The last subject entry in the upper voice is supported in the last two bars with an organ dot on C and additional harmony parts.

Carl Czerny overwrote the fugue with the playing instruction pianissimo e sempre staccato, which is followed by numerous performers. Among the later arrangements of the fugue theme, Paul Hindemith's Ragtime (well-tempered), which was composed in 1921 but not premiered until 1987, should be mentioned here. Hindemith was probably not entirely sure about the effect of this ragtime, as he prefaced it with a reassuring explanation:

“Do you think Bach is turning in his grave? He's not thinking about it! If Bach were alive today, perhaps he would have invented the shimmy or at least included it in decent music. Perhaps he would have taken a theme from the Well-Tempered Clavier by a composer who introduced Bach to him.”

Read more: https://en.wikipedia.org/wiki/Prelude_and_Fugue_in_C_minor,_BWV_847