Holy Scripture opens with the words, "In the beginning God created heaven, and earth." And the catechism adds: Out of nothing he created them. This means that 'before' (one of those false words necessary for human logic, but of course not to be taken literally) God conceived and willed creation, nothing existed -- neither matter nor energy nor images nor motives; not even the mysterious yearning for existence, but actually nothing! God existed, and that was enough. "Beside" God was, is necessary, for he is the "One and All." Even all that is 'in addition' to God comes from him: matter, energy, form, purpose, order, things, events, plants, animals, humans, angels -- everything that is. Man can work with the stuff of reality or even recombine images in the unreal realms of fantasy. But he can never create from nothing, can add no single new thing (real or imagined) to those God has fashioned. For man nothingness is a blank wall. Only God, who can create from it, making things and placing them in reality, has genuine contact with it. For man nothingness is only the severance from things.
Romano Guardini, The Lord, Trans. Elinor Castendyk, 397-398.