In Virgil's day imitation was judged according to how effectively an author stamped his own personality and concerns upon material inherited from earlier writers. Virgil both inherits the tradition and writes against it, probing for the gaps which will allow his personality to emerge, a process described by Harold Bloom as clearing imaginative space. Virgil's moments of authorial comment and self-referentiality help to give his poetry a firmer structure. The Christianization of Virgil has encouraged the legends surrounding his life. Virgil's function within the Commedia is a dual one: he is both a predecessor against whom Dante must write, and Dante's guide and companion within the fiction itself. The significance of Virgil's work to twentieth-century France is born from the conjunction of the historical background against which it is read and an identity preserved by the poetry across the ages, despite the changing roles which it is called upon to perform.