1. The first distinction is the polarity I discover between "self" and "other" as I become aware of my own existence in relationship to other human beings, such as my mother leaning over me in the cradle. This is the discovery of the self and the other as mutual gift.
2. This matures into an awareness of a distinction between the multitude of existents (myself and all others) and the inexhaustible Unity we all belong to, on which we are dependent, which could be called Being. This is the second distinction, the distinction of existents (essentia) from Being (esse). It is the discovery of Being as gift.
3. But if we stayed at this second level, we might conclude that all things are a sort of inevitable unfolding or mechanical self-expression of Being or Spirit (monism, pantheism, idealism). That still leaves actuality itself, along with our sense of Being as gift, unaccounted for. Neither Being (esse) nor existents (essentia) are absolutely prior with respect to the other: existents need Being in order to be, but Being also needs existents to receive it. This is the third distinction, by which we recognize not only that existents depend upon Being, but also that Being depends on existents (polarity, co-dependency).
4. Since Being and existents both differ from and depend upon each other, together they point beyond themselves to something higher or deeper. We find we have to distinguish between the "Being of the world" and the pure Act that makes things exist. Worldly existence (the dual unity of esse and essentia) must be grounded in a necessarily existent Act, pure "is-ness" whose essence is "to be" and which therefore cannot not be. Thus the fourth distinction is between worldly existence and God (also named "subsistent esse", "Beyond-Being", actus purus, or "the Good").
But doing justice to this fourth distinction requires, even philosophically, a notion of creation as distinct from mere emanation. The ground of everything is pure freedom. Thus the distinction is really between God as creator and the World as created – the discovery of the Giver of the gift. Indeed, in the light of revelation, Christ manifests this unconditioned existence of pure Act (equivalent in Hindu philosophy to Nirguna Brahman) as gratuitous, self-giving love (Trinity).
Commenting on the fourth distinction, Balthasar writes: "This mystery of the streaming self-illumination of Being, which was glimpsed by Plato and Plotinus and which alone explains the possibility of a world (that is, the paradoxical existence 'alongside' Infinite Being which fills all things and which stands in need of none), attains its transparency only when, from the sphere of the biblical revelation, absolute freedom (as the spirituality and personality of God) shines in" (Glory of the Lord, V, 626).
He goes on: "God is the Wholly Other only as the Non-Aliud, the Not-Other (Nicolas of Cusa): as He who covers all finite entities with the one mantle of his indivisible Being in so far as they are able to participate in his reality at an infinite remove – as 'entities', which are not Him, but which owe their possibility to his power, and their wealth (to grasp Him as the One who is actual and to shelter in Him) to his creative freedom."