Not that Bob ever misleads us about the sources of his lyrics or anything, tradsteve, but the words have the ring of something that was traditional and then tweaked -- like stength of strings/wings and then "no voice can hope to [hum] sing? tell? say?
See, if you had a different rhyme in the second line -- not "strum" -- the last line could stand as a traditional hymn line. Only the word "hum" makes it odd.
A lot of the imagery is almost traditional hymn wording from the end 1800's.
Mind you, I like the changes. I just want to know where it started.
Blessings,
Barbara