Ach, mein Sinn

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.