Higher ways of causing or existing unify what is diverse in lower ways.
Examples: We can understand something through its opposite, but we can’t sense a thing through its opposite (except perhaps as an illusion or mistake). What the general or CEO gives as a single command requires a multitude of subordinate actions. The higher and more ultimate a goal is, the more it can explain diverse actions with proper goals that are unrelated or incompatible. When you understand what X is, you unify all of X’s, whether actual or possible. Rows and rows of carpentry tools, each with their own limited operation, would have no reason to exist apart from the hand (ditto for the dependence that other tools have on the eye). Higher friendships provide goods that would take a multitude of lower friendships to provide.
Sometimes this higher way of causing or existing is specialized in the lower ways (like the hand tools, the architect, CEO). Sometimes the higher mode in some way depends on the lower one (sense and reason). Sometimes the higher mode gives a sort of dignity to the lower (sense and reason again, a great leader and is subordinates). But these are not always necessary. In the case of friendships, for example, the higher neither specialize, depend on, or give any dignity to merely lower ones; and the nature of a thing doesn’t relate in any of these ways to what takes part in it. There’s no reason why all friendships might not be of the higher sort, and there just is nothing in the formal order other than what the thing is. So each of these qualifications is not essential to being a higher and lower cause or existent. But the unification of what is diverse in lower causes is always necessary.
At the limit of causality and existence, all that causes or exists in any way is unified in The One. To call it The One does not preclude, but in fact requires, that it be described both as one and as many. Again, it does not preclude it being other but requires that it both be self and other. Finally, it does not preclude it being both concrete and abstract, or as individual and intelligible nature. So far as it is “The One”, we speak of ourselves as monotheists, but this speaks precisely of the transcendent unity of one and many, and so our monotheism allows for a multitude in divinity. Again, so far as The One is both self and other, we must understand it as a knower and so a logos, and this self-logos binary is itself spoken of by the same one-many binary. Finally, this self is both a concrete subsistence in the self-logos and also an abstraction. Moltmann was therefore wrong to say that the Augustinian account of the spirit was false because it spoke of the Spirit as “The love between two persons”, and so gave us a “binity” and not a Trinity. This “love” is an abstraction from two concrete beings, to be sure, but this does not give us a “binity” but is a gesture in the direction of how The One is both abstract and concrete. The unity of self-logos, which can only be understood by an act of loving, is not precluded from being God and a self by being an abstraction from concrete selves.
While The One is both self one and many, self-other and concrete-abstract, this does not mean it is any or every other and any multitude, for it cannot be the other an multitude that it causes. Understood as cause, it must always be absolutely and sharply divided from its effects. Still, we can’t help but see causality as a gift of existence, and so if there is to be the gift of existence at all, there must be some unification of created and uncreated existence. At the limit of this unification we must have Incarnation.
But doesn’t all this rationalism violate the necessity of revelation and mystery? Not at all. The One must always be understood as behind the diverse curtains of one-many; self-logos; and abstract-concrete. Any attempt we make to push behind these curtains in fact only uses one curtain to cover the other, while it continues to cover The One. We can call The One “a cause” of both curtains, but this does not allow us to see it-him as one as excluding many, or a self as excluding logos, or a concrete being as excluding abstraction. So far as we limit all possibility to what is one to the exclusion of many, etc., we also judge that The One is (or are) impossible.