The Medieval period in the history of English literature includes a big change from oral tradition to the establishment of written works (in manuscripts). As the example of Arthurian legend shows, both genres influence each other. On the other hand, Chaucer gave an example of how a remarkable author is capable of establishing a norm for his or her followers both in the use of his native tongue as well as the development of literary quality. Future authors had a good example in The Canterbury Tales.