This chorale partita, an imposing set of variations, is probably one of Bach's earliest major organ works. It's thought to date from Bach's late teens, when he was influenced by the partitas of Georg Böhm, organist at the Johanniskirche in Lünegurg, where he was studying; Buxtehude is another likely inspiration. Of course, Bach may have touched up the score later, when he could benefit from a few more years of experience. Bach based the partita on the Lutheran chorale or hymn O Gott, du frommer Gott (Oh God, Thou Just God) and provides a variation for each of the hymn's eight verses. Some have suggested that Bach intended each variation to be played immediately before or after a congregation sang the corresponding verse, although this was not a common practice. Bach may simply have been trying to master variation techniques in a score never intended for liturgical use. Indeed, because this work does not require an organ with pedals, Bach may have intended it for domestic playing on harpsichord or clavichord, or whatever modest organ may have been available. Bach establishes the hymn tune (a variant of the standard version) with block chords. The first variation introduces an obsessive bass ostinato that precedes each elegantly ornamented period of the chorale. The second variation finds a small, rhythmic motif darting from level to level of the three-voice polyphony. The third variation is a toccata, with the melody vibrating in sixteenth notes. The little rhythmic element from the second variation reappears in the fourth, now expanded into scale passages. The unornamented melody reasserts itself in the right hand in the fifth variation, over a syncopated accompaniment. Next, the scales from the previous variation return as the basic material of a new ternary variation in courante form. The partita reaches its expressive high point in the chromatic seventh variation, an ascending and descending tetrachord providing the countersubject for four-voice polyphony. The large, last variation breaks into three parts: an energetic echo-effect section in which the first portion of the hymn becomes a fanfare, a quiet andante, and then a joyous, presto finale.