Lewis with his don hat again. Indeed, one of his earliest works.
Tracing some of the threads of allegory and courtly love through medieval history to the Renaissance. Heavy emphasis on the English part of the development. From Cretien's work to The Romance of the Rose through many English allegories to The Faerie Queen.
Interesting stuff. I would quibble about some points -- that there was, in the early days, so much argument that married couples could not love shows that many people disagreed with it -- but it's a good overview.