For they are by no means to be listened to who suppose that in those times years were differently reckoned, and were so short that one of our years may be supposed to be equal to ten of theirs. So that they say, when we read or hear that some man lived 900 years, we should understand ninety, ten of those years making but one of ours, and ten of ours equalling 100 of theirs. Consequently, as they suppose, Adam was twenty-three years of age when he begat Seth, and Seth himself was twenty years and six months old when his son Enos was born, though the Scripture calls these months 205 years. For, on the hypothesis of those whose opinion we are explaining, it was customary to divide one such year as we have into ten parts, and to call each part a year. And each of these parts was composed of six days squared; because God finished His works in six days, that He might rest the seventh. Of this I disputed according to my ability in the eleventh book. 807 Now six squared, or six times six, gives thirty-six days; and this multiplied by ten amounts to p. 293 360 days, or twelve lunar months. As for the five remaining days which are needed to complete the solar year, and for the fourth part of a day, which requires that into every fourth or leap-year a day be added, the ancients added such days as the Romans used to call “intercalary,” in order to complete the number of the years. So that Enos, Seths son, was nineteen years old when his son Cainan was born, though Scripture calls these years 190. And so through all the generations in which the ages of the antediluvians are given, we find in our versions that almost no one begat a son at the age of 100 or under, or even at the age of 120 or thereabouts; but the youngest fathers are recorded to have been 160 years old and upwards. And the reason of this, they say, is that no one can beget children when he is ten years old, the age spoken of by those men as 100, but that sixteen is the age of puberty, and competent now to propagate offspring; and this is the age called by them 160. And that it may not be thought incredible that in these days the year was differently computed from our own, they adduce what is recorded by several writers of history, that the Egyptians had a year of four months, the Acarnanians of six, and the Lavinians of thirteen months. 808 The younger Pliny, after mentioning that some writers reported that one man had lived 152 years, another ten more, others 200, others 300, that some had even reached 500 and 600, and a few 800 years of age, gave it as his opinion that all this must be ascribed to mistaken computation. For some, he says, make summer and winter each a year; others make each season a year, like the Arcadians, whose years, he says, were of three months. He added, too, that the Egyptians, of whose little years of four months we have spoken already, sometimes terminated their year at the wane of each moon; so that with them there are produced lifetimes of 1000 years.
By these plausible arguments certain persons, with no desire to weaken the credit of this sacred history, but rather to facilitate belief in it by removing the difficulty of such incredible longevity, have been themselves persuaded, and think they act wisely in persuading others, that in these days the year was so brief that ten of their years equal but one of ours, while ten of ours equal 100 of theirs. But there is the plainest evidence to show that this is quite false. Before producing this evidence, however, it seems right to mention a conjecture which is yet more plausible. From the Hebrew manuscripts we could at once refute this confident statement; for in them Adam is found to have lived not 230 but 130 years before he begat his third son. If, then, this mean thirteen years by our ordinary computation, then he must have begotten his first son when he was only twelve or thereabouts. Who can at this age beget children according to the ordinary and familiar course of nature? But not to mention him, since it is possible he may have been able to beget his like as soon as he was created,—for it is not credible that he was created so little as our infants are,—not to mention him, his son was not 205 years old when he begot Enos, as our versions have it, but 105, and consequently, according to this idea, was not eleven years old. But what shall I say of his son Cainan, who, though by our version 170 years old, was by the Hebrew text seventy when he beget Mahalaleel? If seventy years in those times meant only seven of our years, what man of seven years old begets children?