Erbarm dich mein, o Herre Gott BWV 721

This work has been handed down in two versions: `a 2 Clav. e Pedale´ and `Manualiter´ (probably the oldest). I play them both here.
A striking element is the repetitive chord accompaniment. In the aria 'Erbarme dich' from the St. Matthew Passion we find similar repetitive notes in the bass part. My interpretation of that is a persistent knocking on the door that reinforces the call for compassion. That ´s why I choose a not too slow tempo, with a restrained use of rubato.
I have a third version, but I'll save that for tomorrow.