Sir John Eliot Gardiner writes about this cantata: "[Bach] recognized that small lives do not seem small to the people who live them." Bach had an interest in portraying the ordinary anxiety of the guilt-ridden person. Nowhere is this more evident than in Cantata 105 where he focuses on the human rather than the divine. Voices plead "Lord! Lord! Enter not into judgment with your servant." The first two voices seem to shout early! This jarring effect overlaps the apparent beginning of the next section of music. 

In the closing chorale, a quickly pulsating string heartbeat is fast and anxious. Bach incrementally slows it down using longer and longer note values. The result is a  gradual release of pressure, a bizarre and experimental structural device for its time.  "Now, I know, Thou shalt quiet my conscience that torments me."

BWV 105: Netherlands Bach Society

Netherlands Bach Society companion video on the obscurity of the Corno da Tirarsi