Augustine (354-430 A.D.) speculates about the age of the earth and concludes that the Bible is a better source than Ancient Egyptian and Ancient Greek sources

Of the falseness of the history which ascribes many thousands of years to times gone by

Plato's Atlantis described in Timaeus and Critias

Such men are also misled by certain wholly untruthful writings which purport to contain the history of many thousands of years of time.  For we compute from the sacred writings that six thousand years have not yet passed since the creation of man.  Hence, the writings which make reference to far more thousands of years than there have been are vain, and contain no trustworthy authority on the subject.  But we shall not devote a great deal of argument to showing this.  Rather, let us cite only that letter which Alexander the Great wrote to his mother Olympias, giving her the narrative which he had received from a certain Egyptian priest, which the latter had taken from writings held to be sacred among the Egyptians, and which contained an account of kingdoms known also to Greek History.


Ancient sources differ as to the length of the Assyrian, Greek, Persian and Macedonian empires

Belus (the Babylonian god Marduk rather than the legendary king of Assyria) from Guillaume Rouillé's Promptuarii Iconum Insigniorum

According to this same letter of Alexander, the duration of the kingdom of Assyria exceeded five thousand years.  In the Greek history, however, only some 1,300 years are recorded from the reign of Belus himself, whom the Egyptian sources also identify as the first lord of that kingdom.  Again, the Egyptian priest assigns more than eight thousand years to the empire of the Persians and Macedonians down to the time of Alexander, to whom he was speaking; whereas, among the Greeks, 485 years are assigned to the Macedonians down to the death of Alexander, and the Persian empire is reckoned to have lasted for 233 years until brought to an end by Alexander's victory.


Greek and Egyptian history conflict so trust the Scriptures

The Great Sphinx and the Pyramids of Giza, built during the Old Kingdom.

The Greek history therefore gives a much smaller number of years than does the Egyptian.  Indeed, the Greek figures would not equal the Egyptian even if multiplied by a factor of three.  For it is said that, in former times, the Egyptians had so short a year that it ended after only four months; so that the fuller and truer years which both they and we now have would contained three of their old years.  But not even thus, as I have said, does the number of ages contained in the Greek history agree with that given by the Egyptian; and so we must be more ready to have faith in the former, for it does not exceed the true account of the years contained in our writings, which are truly sacred.


The divine books foretold that the whole world would believe in them and the whole world has believed

Page from Codex Vaticanus; ending of 2 Thes and beginning of Heb dating from 300 to 325 AD

Moreover, if the account of the ages given in this celebrated letter of Alexander differs so greatly from things probable and credible, how much less may we believe those other writings which, though full of fabulous accounts of supposed antiquities, our adversaries wish to set against the authority of our most noted and divine books! -- the books which foretold that the whole world would believe in them, and in which, as they foretold, the whole world has indeed believed.  For the truth of the account of the past given in these books is shown by the very fact that their predictions of future evens have been so entirely fulfilled.


Of those who suppose not that this world is everlasting, but either that there are innumerable worlds, or that one and the same world is eternally being born and dissolved at the conclusion of a fixed cycle of ages

In this diagram, the Big Crunch is the universe that is born and dissolved.

There are others who, though they do not believe that this world is everlasting, are of opinion either that it is not the only world, but that there are innumerable worlds, or that it is indeed the only one, but that it arises and perishes at fixed intervals, and that this happens innumerable times.  But those who think in this latter way must necessarily confess that the race of human beings existed before there were other men to beget them.  For, unlike those who think that there are floods and conflagrations which do not affect the entire world, these cannot suppose that, when the whole world perishes, some men always remain, whose offspring then replenish the original population.  Rather, since they believe that the world itself is reborn out of its own material, so also must they believe that the human race is first produced from the elements of the world, and that only then does the  progeny of mortal men, like that of other animals, come teeming from their parents.

What reply is to be given to those who raise the question of the lateness of man's creation

The Creation of Adam is a fresco painting by Michelangelo, which forms part of the Sistine Chapel's ceiling, painted c. 1511–1512. It illustrates the Biblical creation narrative from the Book of Genesis in which God breathes life into Adam, the first man.

When the question of the origin of the world arose, I answered those who refuse to believe that the world has not always existed that -- as even Plato himself most clearly confesses (although not a few people consider that his real belief is at odds with what he says) -- it had a beginning.  Now, in the same way, I replay to those who wonder why man was not created during the innumerable and infinite ages of the past, but was created so late that, as we find in Sacred Scripture, fewer than six thousand years have elapsed since he began to exist.  If it troubles them that, according to our authorities, so short a time has passed since man's creation, and that his years are so few, let them reflect that nothing which has a limit is long, and that, compared to endless eternity, all the expanses of finite time must be considered very little, or, indeed, nothing at all.  For this reason, if we said that there had elapsed not five or six thousand years since God made man, but even 60,000 or 600,000 or 60 or 600 or 600,000 times that number, or this sum multiplied again and again until we came to numbers for which we no longer had a name, we could still ask the same question: Why did He not make man before?

For the eternity during which God refrained from creating man is so great that it stretches backwards from us without any beginning.  Therefore, no matter how great and ineffable the number of ages with which it is compared may be, such an expanse of time, so long as it has a definite conclusion, should not be regarded as being even so big as the smallest drop of water in the entire sea, or, indeed, in the ocean that surrounds the world.  For of these two things, one, indeed is extremely small and the other incomparably great; but both are finite.  And as to that expanse of time which comes forth from some beginning and is terminated by some end: no matter how great its extent, if it be compared with that which has not beginning, I do not know whether to say that we should call in the very smallest thing, or nothing at all.  Suppose we take a finite expanse of time and, working backwards, subtract the briefest moments from it one by one, as you might take one day at a time from a man's life, starting with the day in which he now lives and going back to that of his birth.  Even if the number of moments that you must subtract during this backward progression is so huge that no word can be found for it, this subtraction will nonetheless at some stage lead you back to a beginning.  But now take a time which has no beginning, and, working backwards, take away from it, I do not say tiny moments one by one, or hours, or days, or months, or years, or even periods of years, but expanses of time so great that they cannot be counted by anyone whatsoever.  Subtract expanses of time as great as that which we have supposed to be gradually consumed by the deduction of moments, and subtract them not once or twice or gain and again, but for ever -- and what do you achieve or accomplish by doing this?  You never reach a beginning, for there is no beginning.  Assuming, then, that the mortal condition of mankind continues for so long to decay and be renewed, and assuming also that our posterity remains as weak and ignorant as we are, our descendants might with the same curiosity ask after 600,000 years what we ourselves now ask after a mere five thousand.  The same question might have been put by those who lived before us, when the time of man's creation was still recent.  The first man himself, indeed, might, on the day after he was made, or on the very same day, have asked why he was not made sooner.  And no matter how much sooner he might have been made, this controversy as to the beginning of temporal things would have had no more meaning then than it does not or would have at any later time.

Source: Augustine.  The City of God against the Pagans. Edited and translated by R.W. Dyson. Cambridge: Cambridge University Press, 1998, Book XII, chapters 11, 12, and 13, pages 512 to 516.