In the history of collections of hagiographic texts (legendaries), the last centuries of the Middle Ages are usually considered to have been characterized by a massive diffusion of “abbreviated” legendaries (i.e. ensembles in which lives, passions, and miracles are compiled and reduced) that appeared during the 13th century. While the manufacturers of “traditional” legendaries normally composed their collections from various sources, the scribes were now content to reproduce these new collections without altering them, leading de facto to a certain standardization of hagiographic collections. The aim of our thesis is to reassess this historiographic vision and, more broadly, take the measure of late medieval hagiographic culture by studying all the intellectual operations involved (composition, compilation, copy, use, transformation, and conservation) and by placing hagiographic manuscripts (in particular the legendaries) at the heart of the historical investigation. Rarely studied beyond the texts they convey, these manuscripts are nevertheless magnificent documentary resources for a better understanding of the communities that produced, preserved and read them. On the basis of an in-depth analysis (conducted using disciplines such as palaeography, codicology, philology and techniques from the digital humanities) and a contextualization of these volumes, our thesis project aims to capture the role, functions and uses of Latin hagiographic literature during the last three centuries of the medieval period in a sufficiently original, coherent and diversified geographical setting: the diocese of Trier, an understudied area on the edge of the Germanic and Romance worlds, covering a territory now straddling Germany, Luxembourg, Belgium and France.