Prelude & Fugue No.21

Johann Sebastian Bach

Prelude & Fugue No.21 in Bb major

BWV890 • “The Well-tempered Clavier Book 2: Prelude & Fugue No. 21”

About this work

This prelude takes the form of a substantial courante, initially with a three-voice texture. But Bach frequently abandons one of the voices to accommodate the hand crossings that pervade this piece. Next comes a three-voice fugue, starting in the alto and then entering in the soprano and bass. This little fugue has elements of the trio sonata minuet, and is based on a nervous subject of stuttering eighth notes. Bach manages to pack in two further thematic elements, both fragments of an ascending scale; they combine with the main subject upon their arrival and again toward the fugue's end.