They are deceived, too, by those highly mendacious documents which profess to give the history of many thousand years, though, reckoning by the sacred writings, we find that not 6000 years have yet passed… There are some, again, who, though they do not suppose that this world is eternal, are of opinion either that this is not the only world, but that there are numberless worlds or that indeed it is the only one, but that it dies, and is born again at fixed intervals, and this times without number; but they must acknowledge that the human race existed before there were other men to beget them. For they cannot suppose that, if the whole world perish, some men would be left alive in the world, as they might survive in floods and conflagrations, which those other speculators suppose to be partial, and from which they can therefore reasonably argue that a few then survived whose posterity would renew the population; but as they believe that the world itself is renewed out of its own material, so they must believe that out of its elements the human race was produced, and then that the progeny of mortals sprang like that of other animals from their parents.
As to those who are always asking why man was not created during these countless ages of the infinitely extended past, and came into being so lately that, according to Scripture, less than 6000 years have elapsed since He began to be, I would reply to them regarding the creation of man, just as I replied regarding the origin of the world to those who will not believe that it is not eternal, but had a beginning, which even Plato himself most plainly declares, though some think his statement was not consistent with his real opinion. If it offends them that the time that has elapsed since the creation of man is so short, and his years so few according to our authorities, let them take this into consideration, that nothing that has a limit is long, and that all the ages of time being finite, are very little, or indeed nothing at all, when compared to the interminable eternity. Consequently, if there had elapsed since the creation of man, I do not say five or six, but even sixty or six hundred thousand years, or sixty times as many, or six hundred or six hundred thousand times as many, or this sum multiplied until it could no longer be expressed in numbers, the same question could still be put, Why was he not made before? For the past and boundless eternity during which God abstained from creating man is so great, that, compare it with what vast and untold number of ages you please, so long as there is a definite conclusion of this term of time, it is not even as if you compared the minutest drop of water with the ocean that everywhere flows around the globe. For of these two, one indeed is very small, the other incomparably vast, yet both are finite; but that space of time which starts from some beginning, and is limited by some termination, be it of what extent it may, if you compare it with that which has no beginning, I know not whether to say we should count it the very minutest thing, or nothing at all. For, take this limited time, and deduct from the end of it, one by one, the briefest moments (as you might take day by day from a man’s life, beginning at the day in which he now lives, back to that of his birth), and though the number of moments you must subtract in this backward movement be so great that no word can express it, yet this subtraction will sometime carry you to the beginning. But if you take away from a time which has no beginning, I do not say brief moments one by one, nor yet hours, or days, or months, or years even in quantities, but terms of years so vast that they cannot be named by the most skillful arithmeticians,— take away terms of years as vast as that which we have supposed to be gradually consumed by the deduction of moments—and take them away not once and again repeatedly, but always, and what do you effect, what do you make by your deduction, since you never reach the beginning, which has no existence? Wherefore, that which we now demand after five thousand odd years, our descendants might with like curiosity demand after six hundred thousand years, supposing these dying generations of men continue so long to decay and be renewed, and supposing posterity continues as weak and ignorant as ourselves. The same question might have been asked by those who have lived before us and while man was even newer upon earth. The first man himself in short might the day after or the very day of his creation have asked why he was created no sooner. And no matter at what earlier or later period he had been created, this controversy about the commencement of this world’s history would have had precisely the same difficulties as it has now. (City of God 17.10-12)