 The discussion of Relation shows particularly clearly how Boethius applies logic to analysing God as far as he can, and then shows where and how the logic fails. He needs to explain how it can be true that the same, one God is both the Father and the Son. He does so by claiming that a predication of Relation, such as ‘is the Father’, does not concern the substance of the things related: that a is related to b in no way changes a or b. Moreover, there are some relationships which a thing can have to itself—for example, that of equality. Being-a-father and being-a-son are not, among created things, such relations: no one can be his own father or his own son. But it is here, says Boethius, that creaturely logic breaks down when it tries to comprehend the Trinity: we have in some way to try to grasp the idea of a relation of fatherhood or filiation which is reflexive.