History, Allegory, Tropology

"History is the story of things done, which we find in the literal sense; allegory is when through what is done, something else in the past, present, or future is signified; tropology is when through what is done, something which should be done is signified."

[Hugh's wonderfully pithy definition of these sometimes obscure terms, in his Hugh of Saint Victor on the Sacraments of the Chistian Faith: De Sacramentis