The sources of the allegorical religious trilogy of the Cistercian monk and prior, Guillaume de Deguileville, have not been thoroughly investigated until comparatively recent years. In 1896, Tobler, reporting on Stürzinger's edition of the Pèlerinage de Vie Humaine, stated that Deguileville's characteristics as a poet must be compared to those of Jean de Meun and Daute, and that Deguileville's powers of description did not approach those of Dante. Gröber gives it as his opinion that Deguileville's trilogy was composed without any knowledge of the Divina Commedia, though there are analogies between the two. He cites St. Bernard, Aristotle, the Book of Daniel, the Apocalypse, Dionysius Areopagita, and ms. illustrations, as sources of certain features of Ame. J. E. Hultman, in an excellent study of the poet's life and works, brings to light the sources of a large part of the three poems. His is the first serious attempt to discover the literary antecedents of Deguileville, and is a thorough, though inevitably not an exhaustive, treatment of the subject. Farinelli points out additional analogies between Dante and Deguileville, at the same time denying the possibility of any direct influence.