 Beings are not said to be “in accord with one thing,” therefore, as they would be if they formed a single first-order genus, but “with reference to one thing,” namely, a divine substance that is in essence an activity. And it is this more complex unity, compatible with generic diversity, and a genuine multiplicity of distinct first-order sciences, but just as robust and well grounded, that grounds and legitimates the science of being qua being as a single science dealing with a genuine object of study (Γ.2, 1003b11–16). The long argument that leads to this conclusion is thus a sort of proof of the existence, and so of the possibility, of the science on which the Metaphysics focuses. It is also the justification for the claim, which we looked at before, that the science of being qua being is in fact theology (1026a27–32).