This naturally circumscribed the size of many monastic libraries, and, together with the sheer cost of parchment, helps explains why few medieval monasteries had libraries larger than 500 or 600 volumes. St Gallen possessed around 400 books in the late ninth century; Cluny, one of the richest monasteries in Europe around the twelfth century, had some 570 volumes. Before the thirteenth century, the norm for most monastic libraries was probably not much larger than around 100 or 200 books.

Andrew Pettegree, Arthur der Weduwen, The Library- A Fragile Hist…, loc. 100