Published in 1739, the third part of the Clavier Übung was J.S. Bach’s first organ music to appear in print. It contains preludes on the Catechism and other hymns. It is also his most voluminous and important collection for this instrument. Generally speaking, the music requires three keyboards, including a pedalled one. Together, the first nine arrangements form a Lutheran mass, a ‘missa brevis’. The booklet includes an extensive essay by the performer on the music’s purpose, background and the structure of the entire Clavier Übung, for example he maintains that some of the items were intended for use at home.