Alongside local production, the library has been enriched over the centuries with specimens from the Lombardy area as well as from more distant regions, including the Alcuin Bible, made in the Carolingian era by the French monastic scribe of Tours.
Also from the same period is the very rich donation of Berengario, made famous by the magnificent Eburne diptychs that “bind” the codes, and which today we can admire in the museum, as well as for the absolute value of the volumes they adorned.
In the wake of the Imperial donation, others followed and, more consistently at the beginning of the year 1000, significantly enriched the library.
About sixty new volumes are added only during the course of the twelfth century: they are generally texts of a biblical and liturgical character, donated mainly by canons.
In the centuries immediately following, the heritage of the Library has a partial halt and the small number of manuscripts of non-ecclesiastical nature is the reflection of a cultural environment less vital than before; However, a small repertoire of legal texts surrounding the important collection of the ninth century is interesting as it testifies to the flourishing of the schools of canon law.
During the fifteenth century, the Library is subject to a reorganization, which sees restoration and conservation initiatives of the previous materials present, with the binding of numerous codes. The life of the Library seems to continue quietly until 1797, when the Napoleonic authorities confiscated the entire Library and the Treasury of the Cathedral.
The library materials then become part of the library of Napoleon, which imposes the binding with imperial coat of arms of multiple codes, thus making it de facto, if not impossible, very difficult to reconstruct their history.
With the Treaty of Vienna in 1817, 115 manuscripts were finally returned to Monza, but only one third of the incunabula confiscated by the French. As far as the composition of the materials in the Library is concerned, the liturgical codes represent a substantial part and constitute the richest group of medieval codes.
