Ah God, how much heartbreak in C major, BWV 58

The text has been attributed to Christoph Birkmann by Christine Blanken of the Bach-Archiv Leipzig. He combined the topics of the readings, the gospel of the Flight into Egypt and teaching about the suffering of Christians from the First Epistle of Peter, in a structure of unusual symmetry with a duet as the first and last of the five movements. Both duets are dialogues of the Soul, represented by a soprano, and Jesus, sung by a bass as the vox Christi (voice of Christ). Both duets are set as a chorale fantasia, combining a stanza from a hymn, sung by the soprano as the cantus firmus, with original poetry set in counterpoint. Both stanzas are sung to the same melody, but come from different hymns, Martin Moller's "Ach Gott, wie manches Herzeleid", and Martin Behm's "Herr Jesu Christ, meins Lebens Licht". While the poet wrote the duets to fit the same music, Bach composed them in contrast, even changing the meter of the tune, to fit the different mood: lamenting heartbreak in the beginning, comfort in the end.