It has been suggested that the greatest contribution of "The Canterbury Tales" to English literature was the popularisation of the English vernacular in mainstream literature, as opposed to French, Italian or Latin. English had, however, been used as a literary language centuries before Chaucer's time, and several of Chaucer's contemporaries—John Gower, William Langland, the Pearl Poet, and Julian of Norwich—also wrote major literary works in English. It is unclear to what extent Chaucer was seminal in this evolution of literary preference.