Gregory of Nyssa

Now as for the question, how any single thing came into existence, we must banish it altogether from our discussion. Even in the case of things which are quite within the grasp of our understanding and of which we have sensible perception, it would be impossible for the speculative reason to grasp the "how" of the production of the phenomenon; so much so, that even inspired and saintly men have deemed such questions insoluble. For instance, the Apostle says, "Through faith we understand that the worlds were framed by the word of God, so that things which are seen are not made of things which do appear." … In order, then, to avoid falling into either of these absurdities, which the inquiry into the origin of things involves, let us, following the example of the Apostle, leave the question of the "how" in each created thing, without meddling with it at all, but merely observing incidentally that the movement of God's Will becomes at any moment that He pleases a fact, and the intention becomes at once realized in Nature; for Omnipotence does not leave the plans of its far-seeing skill in the state of unsubstantial wishes: and the actualizing of a wish is Substance.