In the Middle Ages the concept of 'authorship' meant something quite different from our understanding of the word. Authorship as the identification of the original, creative genius behind a work of literature, art or music is quite a modern phenomenon, and post-dates the Renaissance. Authors are now respected for and judged upon their individuality. They enjoy legal rights that protect their works from copying and plagiarism; in turn they are required to respect the rights of other authors, and not to borrow their ideas without acknowledging their sources.
Medieval authors (auctors) were men and women who copied and reshaped existing texts, commenting upon and linking together pre-existing material. Insofar as they were judged, it was on the basis of their knowledge of the sources and their place within a tradition. 'They were not 'authors' in the post-Romantic conception of creative artists/geniuses, given that in most cases they did not have ultimate ownership of the texts on which they worked and reshaped' (Finkelstein and McCleery, 69).
The hand-made nature of manuscripts did not favour the concept of individual authorship. Before the invention of movable type, all books were written by hand, by individuals or teams working in scriptoria. Every book was a collaboration and no two texts were identical. Books were passed between owners over generations and were extremely valuable. Often different owners or readers would make marginal annotations. As books were copied by hand, changes and corrections were made; histories were extended to include more recent events; commentaries and glosses were added to religious texts. Very often any known 'author' associated with the book was not acknowledged in any way. The 'authority' of a text was independent of its association with an 'author'.
The invention of printing revolutionised the means of producing books and promoted the concept of authorship in several ways. The process of printing tended to 'fix' texts. Although readers would continue to comment on and sometimes add to their books, through manuscript notes, these additions were clearly distinct from the printed text itself. Books were produced in vastly greater numbers, and the close, often personal, connection between the writer of a text and its reader was loosened. By the end of the fifteenth century, there was a bewildering array of books to choose from. Printers and publishers needed actively to market their wares, and one way to promote a book was to identify its author. Towards the end of the fifteenth century, the title page was introduced, in which the author's name was displayed prominently. Printing and publishing became 'big business', with a huge capital outlay involved in producing books. Copying was rife, but over the centuries the concept developed of legal rights in a text, in order to protect authors and publishers for illicit copying.