It's not as widely read as his Canterbury Tales, by a long shot, but Troilus and Criseyde, is Chaucer's most perfect and his most moving work — it's his Anna Karenina, the ultimate medieval romance. Troilus is a warrior prince, too proud to be ensnared by love. Criseyde — you may know her as Shakespeare's Cressida — is the changeful widow who embroils him in a wartime romance within the walls of besieged Troy. When Criseyde traded to the Greeks in a prisoner exchange, very bad things ensue. It's as funny, as sad, as psychologically ruthless a portrait of love as any modern masterpiece.