Well-tempered Clavier, Book 2, BWV.870-893

The Well-Tempered Clavier, BWV 846–893, consists of two sets of preludes and fugues in all 24 major and minor keys for keyboard by Johann Sebastian Bach. In the composer's time clavier referred to a variety of keyboard instruments, namely the harpsichord, the clavichord and the organ (which operates using air instead of strings), but not the regal and the then newly-invented pianoforte. The modern German spelling for the collection is Das wohltemperierte Klavier (WTK; German pronunciation: [das ˌvoːlˌtɛmpəˈʁiːɐ̯tə klaˈviːɐ̯]). Bach gave the title Das Wohltemperirte Clavier to a book of preludes and fugues in all 24 keys, major and minor, dated 1722, composed "for the profit and use of musical youth desirous of learning, and especially for the pastime of those already skilled in this study". 20 years later, Bach compiled a second book of the same kind (24 pairs of preludes and fugues), which became known as The Well-Tempered Clavier, Part Two (in German: Zweyter Theil, modern spelling: Zweiter Teil). Modern editions usually refer to both parts as The Well-Tempered Clavier, Book 1 (WTC 1) and The Well-Tempered Clavier, Book 2 (WTC 2), respectively. The collection is generally regarded as one of the most important works in the history of classical music.