Johann Sebastian Bach's chorale harmonisations, alternatively named four-part chorales, are Lutheran hymn settings that characteristically conform to the following: four-part harmony SATB vocal forces pre-existing hymn tune allotted to the soprano part text treatment: homophonic no repetitions (i.e., each syllable of the hymn text is sung one time)
Around 400 of such chorale settings by Bach, mostly composed in the first four decades of the 18th century, are extant: Around half of that number are chorales which were transmitted in the context of larger vocal works such as cantatas, motets, Passions and oratorios. A large part of these chorales are extant as autographs by the composer, and for nearly all of them a colla parte instrumental and/or continuo accompaniment are known. All other four-part chorales exclusively survived in collections of short works, which include manuscripts and 18th-century prints. Apart from the Three Wedding Chorales collection (BWV 250–252), these are copies by other scribes and prints only published after the composer's death, lacking context information, such as instrumental accompaniment, for the individual harmonisations.
Apart from homophonic choral settings, Bach's Lutheran hymn harmonisations also appear as: sung chorale fantasias in some of Bach's larger vocal works hymn melodies for which Bach composed or improved a thorough bass accompaniment, for instance as included in Georg Christian Schemelli's Musicalisches Gesang-Buch harmonisations included in purely instrumental compositions, most typically organ compositions such as chorale preludes or chorale partitas.
History
The compositions by Johann Sebastian Bach that had been printed during his lifetime were nearly exclusively instrumental works. Moreover, by the time Bach died in 1750 it was forgotten that a few of his vocal works (BWV 71, BWV 439–507,...) had indeed been printed in the first half of the 18th century. In the period between the publication of The Art of Fugue in the early 1750s, and the publication of further works from 1900, only one group of Bach's works was published: his four-part chorales.
The most complete 18th century publication of chorales by J. S. Bach is Carl Philipp Emanuel Bach's edition in four volumes, published by Breitkopf from 1784 to 1787. About half of the chorale harmonisations in this collection have their origin in other extant works by Bach. This collection went through four more editions and countless reprintings until 1897. Several other collections of chorales by J. S. Bach were published, some of these using the original C-clefs or different texts.
The loss of musical material from Bach's death to the first printings of chorale collections may have been substantial. Not only are many works the chorales were extracted from no longer extant but there is no way of knowing how much of all the harmonisations that were once compiled the current collections include. For example, there is no way of knowing how many of the 150 harmonisations first proposed for sale in 1764 also appear in Princess Anna Amalia's manuscript which ultimately forms the basis of the Breitkopf edition. As to the chorale melodies with figured bass, current collections include less than one hundred of them whereas those proposed for sale in 1764 numbered 240.
The chorale harmonisations BWV 250–438 were probably all extracted from lost larger vocal works. For six of them the work they have been derived from has been identified. Bach's chorale harmonisations are all for a four-part choir (SATB), but Riemenschneider's and Terry's collections contain one 5-part SSATB choral harmonisation (Welt, ade! ich bin dein müde, Riemenscheider No. 150, Terry No. 365), not actually by Bach, but used by Bach as the concluding chorale to cantata Wer weiß, wie nahe mir mein Ende, BWV 27.
Some harmonisations exist in different keys, i.e. pitches, in 18th-century sources: for instance a Bach cantata autograph gives the four-part chorale in one key, and the same harmonisation is found in one or more of the early chorale compilations in a different key.
Manuscripts
The first record of the existence and sale of groups of collected chorale harmonisations and chorale melodies with figured bass extracted from larger works by J.S. Bach is from 1764, fourteen years after Bach's death. In that year the firm Breitkopf und Sohn announced for sale manuscript copies of 150 chorale harmonisations and 240 chorale melodies with figured bass by J.S. Bach.