Q: Objection 1: It would seem that the universe of creatures, called the world, had no beginning, but existed from eternity. For everything which begins to exist, is a possible being before it exists: otherwise it would be impossible for it to exist. If therefore the world began to exist, it was a possible being before it began to exist. But possible being is matter, which is in potentiality to existence, which results from a form, and to non-existence, which results from privation of form. If therefore the world began to exist, matter must have existed before the world. But matter cannot exist without form: while the matter of the world with its form is the world. Therefore the world existed before it began to exist: which is impossible.

Obj. 2: Further, nothing which has power to be always, sometimes is and sometimes is not; because so far as the power of a thing extends so long it exists. But every incorruptible thing has power to be always; for its power does not extend to any determinate time. Therefore no incorruptible thing sometimes is, and sometimes is not: but everything which has a beginning at some time is, and at some time is not; therefore no incorruptible thing begins to exist. But there are many incorruptible things in the world, as the celestial bodies and all intellectual substances. Therefore the world did not begin to exist.

Obj. 3: Further, what is unbegotten has no beginning. But the Philosopher (Phys. i, text 82) proves that matter is unbegotten, and also (De Coelo et Mundo i, text 20) that the heaven is unbegotten. Therefore the universe did not begin to exist.

Obj. 4: Further, a vacuum is where there is not a body, but there might be. But if the world began to exist, there was first no body where the body of the world now is; and yet it could be there, otherwise it would not be there now. Therefore before the world there was a vacuum; which is impossible.

Obj. 5: Further, nothing begins anew to be moved except through either the mover or the thing moved being otherwise than it was before. But what is otherwise now than it was before, is moved. Therefore before every new movement there was a previous movement. Therefore movement always was; and therefore also the thing moved always was, because movement is only in a movable thing.

Obj. 6: Further, every mover is either natural or voluntary. But neither begins to move except by some pre-existing movement. For nature always moves in the same manner: hence unless some change precede either in the nature of the mover, or in the movable thing, there cannot arise from the natural mover a movement which was not there before. And the will, without itself being changed, puts off doing what it proposes to do; but this can be only by some imagined change, at least on the part of time. Thus he who wills to make a house tomorrow, and not today, awaits something which will be tomorrow, but is not today; and at least awaits for today to pass, and for tomorrow to come; and this cannot be without change, because time is the measure of movement. Therefore it remains that before every new movement, there was a previous movement; and so the same conclusion follows as before.

Obj. 7: Further, whatever is always in its beginning, and always in its end, cannot cease and cannot begin; because what begins is not in its end, and what ceases is not in its beginning. But time always is in its beginning and end, because there is no time except "now" which is the end of the past and the beginning of the future. Therefore time cannot begin or end, and consequently neither can movement, the measure of what is time.

Obj. 8: Further, God is before the world either in the order of nature only, or also by duration. If in the order of nature only, therefore, since God is eternal, the world also is eternal. But if God is prior by duration; since what is prior and posterior in duration constitutes time, it follows that time existed before the world, which is impossible.

Obj. 9: Further, if there is a sufficient cause, there is an effect; for a cause to which there is no effect is an imperfect cause, requiring something else to make the effect follow. But God is the sufficient cause of the world; being the final cause, by reason of His goodness, the exemplar cause by reason of His wisdom, and the efficient cause, by reason of His power as appears from the above (Q. 44, AA. 2, 3, 4). Since therefore God is eternal, the world is also eternal.

Obj. 10: Further, eternal action postulates an eternal effect. But the action of God is His substance, which is eternal. Therefore the world is eternal.