Diana Wynne Jones's autobiography contains an interesting report on what Tolkien lectured about at university:
He started with the simplest possible story: a man (prince or woodcutter) going on a journey. He then gave the journey an aim, and we found that the simple picaresque plot had developed into a quest story. I am not quite sure what happened then, but I know that by the end he was discussing the peculiar adaptation of the quest story which Chaucer made in his “Pardoner’s Tale.”
I am wondering if anyone can recommend particular references on the structure of [quest] plots and how different authors such as Chaucer deliberately varied or subverted them. (A reference only on how Chaucer did this would be interesting enough, as well)
I'm familiar already with works like Propp's morphology of the folktale, which is close but tends to discuss more of the commonalities and less on contrast or variation.
Thanks for your help!