'Third part of the Clavierubung consisting of various preludes on the catechism and other hymns for organ: For lovers and especially for connoisseurs of suchlike works, to refresh their spirits, provided by Johann Sebastian Bach,Royal Polish Court Composer and to the Elector of Saxony, and to the Director Chori Musici in Leipzig. Published by the author’ The 3rd book of the Clavierubung was the first collection of organ music published by Bach, and is his largest collection of works for the organ. The 1st part of the Clavierubung appeared in 1731 and consisted of the Partitas BWV 825-830 (published as his Opus1), and was followed by t6he 2nd part in 1735 which included such well know works as the Concerto in the Italian Style and the French Overtures BWV 831 and 971. Parts 1&2 are for harpsichord, the latter for an instrument with 2 keyboards. The 3rd part calls for an instrument with 3 keyboards (i.e the organ pedals), and requires an organist of considerable ability to perform its works. It is interesting that the inscription refers specifically to connoisseurs, a reference to the greater ability required from the performer. The work has been likened to a German Organ Mass, and although it does contain a Kyrie and Gloria, but there is no Agnus Dei. There is a lot more music than would be required for an organ mass. In fact the collection can be divided in to 3 parts - a Missa brevis (Kyrie and German Gloria) which form a Lutheran Mass - there are 9 arrangements of these settings. Second there is a group of 12 arrangements of Catechism songs. The 3rd section moves away from the church and into more domestic music. The Four Duets can be played on either the harpsichord or organ, and this suggests their suitability for domestic music making. This is Bach’s magnum opus for organ.