The modern notion of a book is very unlike the medieval one, and medieval attitudes to textuality, authorship and authority are significantly different from modern ones too. Modern readers have access to many medieval texts in recent editions or translations, and so it is easy to overlook how these printed versions differ from medieval manuscript copies, and how the mentality of our print-culture age differs from that of a manuscript culture.
Medieval European culture was fundamentally oral rather than written, in that the commonest means of composing and transmitting most texts (in the sense of imaginative stories and poems and also formal, legal and ritual discourses) was by speaking them aloud from memory and/or imagination.…
Swan, Mary. "Medieval Manuscript Culture". The Literary Encyclopedia. First published 04 September 2003
[http://www.litencyc.com/php/stopics.php?rec=true&UID=1324, accessed 24 February 2017.]