The works collected and revised by Bach probably between 1744 and 1747 and included in the so-called Leipzig Autograph, the Leipziger Originalhandschrift, were largely composed between 1708 and 1717, the years spent in Weimar. The chorale, the congregational hymn of the German Protestant church, had its roots in pre-Reformation practices. Its importance in Lutheran church music may in some respects be compared with the importance in Catholic tradition of plainchant, itself a source for some chorale melodies. As in other fields of music, Bach's varied treatment of the chorale sums up and crowns a long tradition.

The Leipzig Autograph opens with a Fantasia on Komm, Heiliger Geist (Come, Holy Ghost), in organo pleno, il canto fermo nel pedale (for full organ, the chorale melody in the pedal part). The chorale itself is a German version of the antiphon Veni, Sancte Spiritus, devised by Martin Luther for congregational use. An imitative contrapuntal introduction, in which three upper voices enter in turn over a sustained pedal-note, leads to the chorale melody itself, in the lowest register, chorale phrases separated with passages of varying length for the manuals. A second treatment of the same chorale, for two manuals and pedals, is in triple metre, with a fugal subject derived from the chorale, the manuals preceding the pedal entry in each section. This extended composition ends with a particularly splendid coda.

An Wasserflüssen Babylon (By the waters of Babylon), for two manuals and pedals, uses a fifteenth century chorale melody from Strasburg. .Here the chorale melody is first heard in the top part, imitated in the tenor, which itself introduces the continuation of the chorale theme. This is followed by Schmücke, dich, o liebe Seele (Deck thyself, beloved soul), much admired by Schumann and based on a mid-seventeenth century chorale, first suggested in the alto part in a contrapuntal introduction, before appearing in the soprano in augmentation, its notes prolonged.

The Trio on Herr Jesu Christ, dich zu uns wend (Lord Jesus Christ, turn to us) is again based on a mid-seventeenth century chorale. Here the three contrapuntal parts interweave, the left hand entering in canonic imitation of the right over a pedal-part derived from the opening notes of the chorale. This opening figure brings, in conclusion, a pedal statement of the melody, accompanied by the continuing counterpoint of the two upper parts.

O Lamm Gottes, unschuldig (O Lamb of God, guiltless, slaughtered on the Cross) is based on a Lutheran version of the Agnus Dei, O Lam Gades unschüldig, by Nikolaus Decius, an early follower of Luther. This, one of the earliest chorales, is itself derived from plainchant. The three sections of the Agnus Dei allow three different treatments of the cantus firmus, which appears first in the top part, then in the middle part and finally in the pedals.

Nun danket alle Gott (Now thank we all our God) is based on a seventeenth century chorale. Counterpoint based on the melody precedes the entry of the chorale itself in the upper part, a procedure that is followed throughout, in the manner associated particularly with Bach's elder brother's teacher, Pachelbel. Von Gott will ich nicht lassen (From God I will not part) treats a sixteenth century chorale dating from 1572 in Erfurt. Here again, each section of the melody, played on the pedals, is introduced by a preceding contrapuntal section derived from the hymn itself.

Writer: Keith Anderson