For the student of fiction, the most noteworthy accomplishment of Guillaume de Lorris in the Roman de la Rose is his invention of large-scale psychological allegory. C. S. Lewis, who has taught us how to haead the poem, suggests that it is an offspring of Old French romance and the moral allegory of the Prudentius tradition: the Roman deals with the erotic content of the romances in a form made newly potent by the moral allegorists of the school of Chartres. Lewis sees an adaptation or borrowing of allegory by romance before Guillaume in Chrétien de Troyes. There, it is suggested, we can see narrative poetry taking over allegory as a tool whenever psychology is in question. The purpose of this paper is to amplify the history of psychological allegory at this point, and thereby to modify Lewis' admittedly general account. Thus, while there are excellent reasons for using Chrétien as the exemplar of courtly romance writing, it can be shown that the tendency toward allegory in the romances is considerably more extensive than his practice would indicate. The romances constitute a virtual encyclopedia of psychological personifications, including illustrations and discussions of most of the “characters” in the Roman de la Rose. More important, this tendency does not represent simply a borrowing of the forms and procedures of moral allegory. Indeed, the allegory developing within the romances is not even so much a modification of the pre-established species as an independent invention. Specifically designed for psychological analysis, it points to the unique structural achievement of Guillaume de Lorris.