I have read the first six Questions of the Summa, and each Question consists of several long Articles. Within each Article is a statement, objections to the statements, a contrary answer, and a defense of the statements. St. Thomas did not follow this model in “On the Eternity of the World”, but made it a sort of letter or instruction. There was no debate to be had in this subject; instead, it’s a solemn teaching not open to variations.
This short article makes a distinction between a thing that existed forever without requiring God to create it, and a thing that existed forever by virtue of God having created it. Remember that God is in eternity, and in a sense He IS eternity, just as He is majesty, glory, beauty, etc., and thus anything created by God can even be created in the eternal state. I suppose Aquinas is venturing into a sort of Eastern quasi-emanationism, whereby the things that exist emanate and flow from God eternally.
Either way, this is an OPUSCULA, not a SUMMA or DOCTRINAL THESIS. That means it is a speculative letter on theory. He is experimenting with Platonism and Aristotelianism, trying to mesh the notions together. It’s really fascinating, but hardly a ground for worry.
Everything Thomas talks about is based in the idea of actuality vs. potentiality. If a thing is actual, it is in a state of total completion. A thing may be said to be in actuality if it is in a state of rest, and fulfilled in its goal, and a thing may be said to be in potentiality if it is able to become something which it is not; however, everything we observe in the universe is not only actual in some way (existing as it is), but potential too (it may become something different). For example, a burning log is
actually hot - but it is, at exactly the same time,
potentially cold and potentially soot, because it is tending toward becoming a pile of ashes due to the laws of physics and chemistry. Another example is a dog: a living dog is actually alive and potentially dead, but never actually dead and potentially alive. The fact that the dog is alive, but not dead, means that this dog has not reached every possible state it could be in, and never will reach every state it could be in, because some of its possible states are plainly contradictory to the others. The Dog is not truly full in its “doggishness” when it is alive, nor when it is dead, because the fullness of a dog is to be actually alive OR actually dead. Since both of these states are contrary to one another, a dog is never “complete”, never totally actualised and at rest. The same can be applied to humans, flowers, interstellar dust, or dark matter - this is why we believe there must be a thing outside potentiality, who is simply in a state of total actuality, total perfection, total reality, total rest, total self-knowledge and total unity in of itself - otherwise, nothing could have come into existence because all things would be shifting
potentials, not stable
actuals.
Apply actuality/potentiality to the Universe, and you see many possibilities. God may just have created something with a perfect state of actuality, but only in so far as it was granted His perfect actuality. We might say that the “world” (Aquinas doesn’t mean planet Earth, but the Cosmos) is fashioned from some ineffable, eternal reality that God ‘resides’ in. He needs no space, nor time to measure that space, but it is possible that God fashioned this world, via the “Big Bang”, out of some material He caused to be - but in eternity! It’s really mind-bogglingly wonderful.
but was thinking about this last night and I feel rather glorious stupid here. But for me this question immediately made me think of the Incarnation, of the one point in time when eternity met linear time. God taught me, or I’m trying to be as precise as possible, when He maybe enlightened my understanding as to the Incarnation that it would be best to view the world as having started at that point in linear time and moved outward causally. That understanding, now that I’m Catholic and know explicitly Catholic teachings, for example makes the doctrine of the Immaculate Conception make sense.