All Bach arias are duets. This is the first of two episodes on BWV 21, which is one of Bach's earlier works. It's a cantata rich with meaning, with biblical truths spread out from the Psalms to Revelation. And, Alex has a revelation of his own about Bach arias -- sparked by this very piece. Performance of this cantata by the Netherlands Bach Society (Shunske Sato, director): https://www.youtube.com/watch?v=JGT0iPpU9is