The mystery of the incarnation

None of them says anything about “how” the Incarnation took place: they simply witness to the fact of the Incarnation.

This might serve as a hint to the theologian not to want to know too much about “how” these things can be, and to abandon all subtle considerations and distinctions. It will be sufficient for us to say that the order of knowledge—that in the historical Revealer, we know the Eternal Son of God—corresponds to an order of being, which goes in the opposite direction: that the Eternal Son became man, that He who is from everlasting entered into human history, that it is precisely this entrance into history which constitutes the basis of His threefold work. All that goes further than this is useless speculation.—Emil Brunner, The Christian Doctrine of Creation and Redemption, 351–52