Libraries, handbooks, and encyclopaedias collect, arrange, and present books, texts, and/or information. This is reflected not least in the polysemy of the term 'library' (βιβλιοθήκη, bibliotheca ) in Roman and later times: it can denote public institutions functioning in representative architectural spaces, physical book collections, but also collections of texts, regardless of the actual physical books that contain them, and even works that condense whole physical libraries into new texts. The present volume explores this range of knowledge repositories from physical spaces and objects to the virtual level of texts by enquiring into their religious connotations, functions, and contents. How can we interpret the spatial integration of libraries into sanctuaries or monasteries? How do religious conceptions of education shape the perception of knowledge, books, and libraries? What roles do knowledge repositories play in projects of religious or spiritual formation? By asking these questions for selected case studies, the contributors highlight crucial aspects of the interplay between learning and religion from Hellenistic to Carolingian times and offer a more nuanced understanding of how religion works in ancient and medieval contexts.