  However that may be, once the notion of a relation of reason is introduced in the Latin West, it becomes pervasive—so pervasive, in fact, that even philosophers, such as Ockham, who complain that such a notion is “not to be found in the writings of Aristotle” and that “‘relation of reason’ is not a philosophical term,” nevertheless feel compelled to give some account of it in order to preserve common  usage.[36]  The pervasiveness of this notion is explained at least partly by the fact that medieval philosophers think it can be used to clarify and explain a number of troublesome non-paradigmatic relational situations. For example, by the end of thirteenth century, most philosophers use it to explain the doctrine of creation, saying that creatures are related to God by a real relation, whereas God is related to them by a mere relation of reason (cf.  Henninger 1989). Again, many use the notion to clarify certain cases of relational change. Thus, when a substance acquires a new relation without undergoing any real change this is often explained by saying that the substance acquired a mere relation of  reason.[37]  Finally, some medieval philosophers use relations of reason to identify a sense in which God can have accidents after all. Since relations of reason are mere projections (or properties a thing has by virtue of the activity of some mind), we can conceive of them as accidents in a broad sense—that is, as properties or features that a thing can both acquire and lose. But since the acquisition or loss of these properties does not require a subject to undergo any real change, some medievals claim that there is no reason in principle why even God should not have accidents of this  sort.[38]