Prologus Galeatus and the Vulgate Prefaces

Jerome's Prologus Galeatus, along with his other Vulgate prefaces, is his own primary statement, from the late fourth century, distinguishing the books of the Hebrew canon from those the church read but did not use to establish doctrine, the origin of the later Protestant and Catholic division over the deuterocanonical books. As Jerome's own primary text it is the correct source for what he himself argued about canon at the time. Its limit is that it records one influential scholar's own position within an already contested question, not a later church council's binding determination, so a claim about how the canon was actually settled needs a conciliar or historical source in addition to Jerome's preface.