City of God

For if eternity and time are rightly distinguished by this, that time does not exist without some movement and transition, while in eternity there is no change, who does not see that there could have been no time had not some creature been made, which by some motion could give birth to change—the various parts of which motion and change, as they cannot be simultaneous, succeed one another—and thus, in these shorter or longer intervals of duration, time would begin? Since then, God, in whose eternity is no change at all, is the Creator and Ordainer of time, I do not see how He can be said to have created the world after spaces of time had elapsed, unless it be said that prior to the world there was some creature by whose movement time could pass.

And if the sacred and infallible Scriptures say that in the beginning God created the heavens and the earth, in order that it may be understood that He had made nothing previously—for if He had made anything before the rest, this thing would rather be said to have been made “in the beginning,”— then assuredly the world was made, not in time, but simultaneously with time. For that which is made in time is made both after and before some time,— after that which is past, before that which is future.

But none could then be past, for there was no creature by whose movements its duration could be measured. But simultaneously with time the world was made, if in the world's creation change and motion were created, as seems evident from the order of the first six or seven days. For in these days the morning and evening are counted, until, on the sixth day, all things which God then made were finished, and on the seventh the rest of God was mysteriously and sublimely signalized. What kind of days these were it is extremely difficult, or perhaps impossible for us to conceive, and how much more to say!