Cantata no. 135: Ach Herr, mich armen Sünder, BWV.135

Johann Sebastian Bach composed the church cantata Ach Herr, mich armen Sünder (Ah Lord, poor sinner that I am), BWV 135 in Leipzig for the third Sunday after Trinity and first performed it on 25 June 1724. It is the fourth chorale cantata from his second annual cycle, and is based on the hymn by Cyriakus Schneegass.

In the format of Bach's chorale cantata cycle, the words of the hymn are retained unchanged only in the outer movements, while an unknown contemporary librettist paraphrased the inner stanzas for recitatives and arias. Bach structured the cantata in six movements, setting the chorale tune in a chorale fantasia in the opening movement, and in a four-part setting in the closing movement. The two choral movements frame alternating recitatives and arias of three vocal soloists. Bach also used a four-part choir, and a Baroque instrumental ensemble of cornett, trombone, two oboes, strings and continuo. He set the first movement as a polyphonic chorale fantasia, the bass sings the cantus firmus.