Das Wohltemperirte Clavier, a collection of preludes and fugues in all major and minor keys completed by Johann Sebastian Bach in 1722, was clearly modeled along the lines of Ariadne Musica by Johann Caspar Ferdinand Fischer (1662-1746, Kapellmeister in Baden from 1715 to 1746) - an organ music anthology published for the first time in 1702 and probably known by Bach in it's second 1715 edition. Bach took Fischer's original layout of 20keys and expanded it to a total of 24, thereby creating the first self-contained collection of music written for the entire corpus of existing keys. Bach, who, on the handwritten title page of the beautiful copy now preserved in the Berlin Staatsbibliothek (Mus. Ms. P 415), signed as Hochf. Anhalt-Cöthenischen Capel-Meistern und Directore derer Cammer Musiquen, clearly indicated his purpose in composing this incomparable collection: "for the profit of musical youth desirous of learning, and especially for the pastime of those already skilled in this study..."