The title of the episode is from "The Allegory of Love: A Study in Medieval Tradition", a book by C.S. Lewis. It is an influential exploration of the allegorical treatment of love in the Middle Ages and the Renaissance.
The line "The heart can and should obey the head" is credited to C. S. Lewis. It's a shortened version of a sentence in his book "The Abolition of Man". The exact quote is "The heart never takes the place of the head: but it can, and should, obey it."
Lewis Carroll is referenced a number of times. The name of Dorian's fiancée is Alice, the same as Carroll's most famous character. Alice says she was "grinning like a Cheshire cat" in the photo of her and Dorian, a reference to a character in Alice's Adventures in Wonderland.