  Aristotle’s Metaphysics did not become available to philosophers in the Latin west until the mid-twelfth century, and it did not circulate widely before the thirteenth. Nonetheless, philosophers throughout the medieval period denied that all relational situations conform to the Categories paradigm. Unlike Aristotle, however, the basis of the medievals’ denial was largely theological in nature. Considerations associated with the doctrine of creation, for example, led them to accept relational situations in which two (or more) substances are related by a single property or accident. And considerations associated with the Christian doctrine of the Trinity forced them to admit that, in certain relational situations, even substances themselves can qualify as  relations.[6]  Prior to the fourteenth century, however, these sorts of situations were regarded as special cases, rare exceptions to a general rule. Indeed, prior to this time, most philosophers worked hard to show that even these sorts of situations conform, at least to some extent, to the paradigm of the Categories. This effort, as we shall see, helps to explain the pervasiveness in late medieval philosophy of the distinction between so-called real relations (relationes reales) and mere relations of reason (relationes rationis).