generations.

The medieval book trade was a second-hand trade even as with 
the dealing today in old masters. 

*     Then, from the twelfth century onwards the rise of the 
universities brought masters and students into the field of 
book production in class time, and these books found their way 
back to the monastic libraries when students returned after 
completing their studies: “A number of these standard 
textbooks, of which approved exemplars were kept for copying 
by the stationarii  of the universities, naturally found their way 
into print quite early, for many of them continued in 
undiminished request in the fifteenth century as before. These 
official university texts offer no problems of origin or 
nomenclature. . .” (p. 102) Goldschmidt then adds, “Soon after