For medieval monasteries, composing a cartulary was a strategy of memory. In this paper I argue that in the case of historical or commemorative cartularies - i.e. cartularies in which copies of charters were prefaced by, or interwoven with, a narrative about the origins of the institution or the deeds of its abbots - it even amounts to a canonization of the past. To illustrate this, two cartularies belonging to this category are examined in some detail, namely the two libri traditionum of St Peter’s Abbey in Ghent. The first, known as the Liber Traditionum Antiquus (LTA), was composed between 944 and 946, shortly after the so-called restoration of the monastery by Count Arnulf I of Flanders; the second Liber Traditionum (LT) was compiled in 1042 or immediately thereafter, in the wake of the reform of Richard of St Vanne. An analysis of their structure and contents shows how the authors of both copybooks interpreted and adapted their monastery’s past to suit the needs of their own time. More particularly, the two libri traditionum retain what the Benedictine monks of that period wanted to be remembered. Composing such a cartulary was therefore both a codification and a canonization of the past: a codification because it fixes the interpretation of the archival memory and in this way organizes and stabilizes the past in a coherent and usable form; a canonization because it is based on a process of selection and exclusion. Following the conceptual framework developed by Aleida and Jan Assmann, ‘the canonization of the past’ is defined as the elevation of the past - or rather of a particular interpretation of that past - to the status of norm or point of reference. As historical or commemorative cartularies such as the two libri traditionum of the St Peter’s Abbey in Ghent store all the information that is considered vital for the existence and continuation of the monastic community in a coherent and usable form, they enshrine a past that is elevated to a normative and hence canonized status.