Text-books are linked directly to the curricula of schools and universities and their history reflects the evolution of institutional teaching. In the sixteenth century, student notes were often printed without the consent of the lecturer/author. Thereby a type of material previously restricted to a fairly local area became accessible throughout Europe; this, in turn, weakened local traditions. While the teaching within individual institutions became less uniform, European universities with similar religious attitudes became more alike, as the same, or similar, text-books became available throughout the Continent. Many grammar, logic and rhetoric text-books were in use in the later Middle Ages, but many had lost their text-book function, themselves becoming the basis for extensive and advanced commentaries. Several of John Vaus's books can be related to his work on the Doctrinale. Vaus explained that he had chosen to work on the Doctrinale because that was the text his students would expect to use.