Stilly River Sage---the Moyers Special a while back was a wonderful history of the song---I taped the audio of it.   Featured, among many others in interviews Jesse Norman.

I, too, heard the program with Turner that was webcast on the Dianne Reahm show.   Intersting---though she seems a bit stilted. The explanation that he gave about how the word "wretch" was changed to "soul" and really did not hold the significance then that it should--"wretch" being a better word in the song seemed, to me, incorrect. My understanding is that Paul Robeson changed it to "soul"--as he changed other lyrics (Old Man River for one) to convey a purer thought---his comment--as I understand it is--"...we are not wretches we are all God's souls"

Bill Hahn