Christoph Wolff, Adams University Professor for the Harvard Department of Music and author of Johann Sebastian Bach: The Learned Musician (published by Norton in 2000), can be heard lecturing on the great Mass in B-Minor here at the Indiana University website. The website not only offers audio of the lecture, which includes live (and well-done) "examples" by the University, but links to the visuals that Wolff used.

You can also listen to the University's performance of the Mass in B-Minor.

The sometimes technical nature of this lecture (which focuses in large part on the Credo) may be hard for some to follow, but worth struggling through all the same, with the hopeful result that one may cultivate a greater appreciation for this important, beautiful, and (frankly) edifying work.