As organist at Weimar, Johann Sebastian Bach was charged with providing a harmonic underpinning for the singing of Lutheran chorale tunes chosen for each day. Bach wrote out many of these harmonizations, in part as instruction for younger composers (they are still used for this purpose). A derivation of this practice, Bach's conception of the organ chorale, as manifested in the chorale preludes, dates from 1713 -1714, about the time he became familiar with Vivaldi's concertos.
Bach's Orgelbüchlein (Little Organ Book) contains chorale preludes for the church year written during the composer's service at Weimar (1708 - 1717). In about 1713, Bach began assembling the Orgel-Büchlein, and his earliest entries seem to be Her Christ, der ein'ge Gottes-Sohn, BWV 601, In dulci jubilo, BWV 608, Christ ist erstanden, BWV 627, and Heut' triumphieret Gottes Sohn, BWV 630. These were very original compositions, highly expressive miniatures based on a chorale melody, supported with refined counterpoint, and featuring highly condensed motivic writing.
Bach's Orgelbüchlein was essentially complete by 1716. Only the fragment O Traurigkeit and the chorale prelude, Helft mir Gottes Güte preisen, BWV 613, were added later. "Complete" is used with some reservation here, because Bach originally projected 164 pieces but completed fewer than 50. In Bach's manuscript, pages with finished pieces alternate with blank ones intended for other chorale preludes. The later pieces differ from Bach's earlier chorale elaborations, in that they contain only one statement of the melody and are intended to demonstrate how to accompany a chorale with contrapuntally proper figurations that support the meaning of the text.
In the early 1740s Bach assembled a number of chorale preludes, possibly with the intention of publishing them as a set. These Achtzehn Choräle (Eighteen Chorales) BWV 651 - 668 were almost certainly written before 1723 and revised later. The Fantasia super Komm, heiliger Geist, BWV 651 is an especially impressive, extended elaboration of the chorale melody, which is in the pedal. The tune is treated in a less ornate fashion in the next prelude of the set (BWV 652). The highly convoluted Von Gott will ich nicht lassen, BWV 658 also contains the chorale melody in the pedal.
The six Schübler chorales (BWV 645 - 650) are derived from Bach's cantatas and contain one of his most popular chorale preludes, on the melody Wachet auf, ruft uns die Stimme, BWV 645.
The third part of Bach's Clavier-Übung, published in Leipzig in 1739, contains 21 chorale preludes (not all appear in every publication), many of which are for manuals only. Nine of these are meant for use during the Mass, while the others are for the catechism. Among the most impressive is Kyrie, Gott heiliger Geist, BWV 671, which is in five voices with the chorale melody in the pedal. More complex is the first of two preludes on Aus tiefer Not schrei ich zu dir, BWV 686, which is in six parts, including two pedal parts.
