Augustine of Hippo : It is necessary, therefore, to preserve the series of generations descending from Shem, for the sake of exhibiting the city of God after the flood. As before the flood it was exhibited in the series of generations descending from Seth, now it is descending from Shem. And therefore does divine Scripture, after exhibiting the earthly city as Babylon or "Confusion," revert to the patriarch Shem and recapitulate the generations from him to Abraham, specifying the year in which each father gave birth to the son that belonged to this line and how long he lived. And unquestionably it is this that fulfills the promise I made, that it should appear why it is said of the sons of Eber, "The name of the one was Peleg, for in his days the earth was divided." For what can we understand by the division of the earth, if not the diversity of languages? And, therefore, omitting the other sons of Shem, who are not concerned in this matter, Scripture gives the genealogy of those by whom the line runs on to Abraham, as before the flood those are given who carried on the line to Noah from Seth. Accordingly this series of generations begins thus: "These are the generations of Shem: Shem was a hundred years old and begat Arpachshad two years after the flood. And Shem lived after he begat Arpachshad five hundred years and begat sons and daughters." In like manner it registers the rest, naming the year of his life in which each begat the son who belonged to that line that extends to Abraham. It specifies, too, how many years he lived thereafter, begetting sons and daughters, that we may not childishly suppose that the men named were the only men, but that we may understand how the population increased and how regions and kingdoms so vast could be populated by the descendants of Shem. Especially this is true of the kingdom of Assyria, from which Ninus subdued the surrounding nations, reigning with brilliant prosperity and bequeathing to his descendants a vast but thoroughly consolidated empire, which held together for many centuries. — City of God 16.10 Augustine of Hippo : But to avoid needless prolixity, we shall mention not the number of years each member of this series lived but only the year of his life in which he gave birth to his heir, that we may thus reckon the number of years from the flood to Abraham and may at the same time leave room to touch briefly and cursorily upon some other matters necessary to our argument. In the second year, then, after the flood, Shem when he was 100 years old begat Arpachshad; Arpachshad when he was 135 years old begat Cainan; Cainan when he was 130 years begat Salah. Salah himself, too, was the same age when he begat Eber. Eber lived 134 years and begat Peleg, in whose days the earth was divided. Peleg himself lived 130 years and begat Reu; and Reu lived 132 years and begat Serug; Serug 130, and begat Nahor; and Nahor 79, and begat Terah; and Terah 70, and begat Abram, whose name God afterwards changed into Abraham. There are thus from the flood to Abraham 1, years, according to the common or Septuagint versions. In the Hebrew copies far fewer years are given, and for this either no reason or a not very credible one is given. — City of God 16.10 Augustine of Hippo : When, therefore, we look for the city of God in these seventy-two nations, we cannot affirm that while they had but one tongue, that is, one language, the human race had departed from the worship of the true God. Nor can we conclude that genuine godliness had survived only in those generations that descend from Shem through Arpachshad and reach to Abraham. But from the time when they proudly built a tower to heaven, a symbol of godless exaltation, the city or society of the wicked becomes apparent. Whether it was only disguised before or nonexistent, whether both cities remained after the flood—the godly in the two sons of Noah who were blessed and in their posterity, and the ungodly in the cursed son and his descendants, from whom sprang that mighty hunter against the Lord—is not easily determined. — City of God 16.10 Bede : These are the generations of Shem. Shem was one hundred years old when he begot Arphaxad, two years after the flood. After the destruction of the Tower of Babel, Scripture hastens, by enumerating the generations of the second age of the world (for the first had run until Noah and the flood), to arrive at Abraham, the patriarch of the third age, indeed of all nations; through whose faith and obedience the new foundations of the holy city would once again be laid, and in whose seed the dispersion of nations would return to one confession and faith in divine worship. But the number one hundred, which is transferred from the left hand to the right, usually insinuates great perfection whether of good action or of hope or heavenly life; fittingly Sem, the son of blessing, in the hundredth year of his life begot a son, whose lineage would come from Heber and reach to Abraham; and Abraham himself, by the same grace of the sacrament, begot Isaac the son of promise in the hundredth year of his own age, in whose example we, the children of the promise, as if placed temporarily on the right side of our judge through hope, expect the blessing of heavenly life through good works: for the two sons whom Sem begot before the hundredth year, Elam and Asshur, as read above, placed outside the holy seed and as if retained still in the left hand, created citizens of the earthly city rather, that is, of this world. For one became the father of the Elamites, that is, the Persians, the other the progenitor of the Assyrians. But a great question according to the literal sense arises for us as to how Shem can be said to be one hundred years old two years after the flood, when he is asserted above to be born in the five hundredth year of Noah, and it is read that the flood came in the six hundredth year of that same Noah. For if he was born in the five hundredth year of his father, surely when Noah was six hundred years old when the flood came, he was one hundred years old, and thus two years after the flood, he had one hundred and two years of age. Therefore, that the number of times does not contradict itself, it must be understood either that Noah had a little more than five hundred years when Shem was born, or two less than six hundred when the flood came, or that Shem was one hundred and two years old when Arphaxad was born. For Scripture is accustomed to speak in such a way that even if a little remains or is lacking, it still sounds a complete and perfect number in the count. However, it seems most probable, as my suspicion leads me, that when Shem was born, Noah had a little more than five hundred years; for indeed Scripture did not lie in saying that he had five hundred years, even if he had five hundred and two: for the smaller number is certainly contained within the greater. For Scripture itself signified that it spoke very freely in that place when it said Noah having five hundred years begot three sons, Shem, Ham, and Japheth; when it is not in doubt to anyone that one man cannot beget three sons from one wife in one and the same year: which perhaps sacred history more diligently took care to explain in this place, by saying Shem was one hundred years old two years after the flood because it remembered that it noted his year of birth somewhat negligently. — Commentary on Genesis (Hexaemeron) Ambrosiaster : WHY DOES GOD EXPRESS HIMSELF THUS: "MY SPIRIT SHALL NOT ABIDE IN MEN, BECAUSE THEY ARE FLESH, AND THEIR DAYS SHALL BE NO MORE THAN A HUNDRED AND TWENTY YEARS? — The giants who were then on the earth, superb and wicked men, proud of the size of their stature, obeying the desires of their flesh, and apostates from birth, displeased sovereignly in God. It was then that he declared that mankind would perish by the deluge, and he set the time to allow time for correction to those whom the just threats of his indignation would touch with repentance. It was for this reason that the construction of this ark lasted a hundred years. Twenty years elapsed before Noah began to build it. But the narrative seems to throw obscurity on what it adds after speaking of the years of Noah. The sentence of God was carried before Noah had reached the age of five hundred years. And he said, "My Spirit shall not abide in these men," and he adds: “Because iniquity has increased on the earth, I will cut off from the earth, from man up to the animals (Gen. 6:3),” the prediction that the flood undertook to accomplish. Now we know that after the flood the life of men was prolonged for a great number of years; Aaron, the brother of Moses, lived a hundred and twenty-three years. If Moses had not lived beyond a hundred and twenty years, it is because he did not glorify God (Num. 38:38), for without this sin of definition he entered in the promised land. (Num. 27:14.) Some believe that the fact of the high priest Jo'ada, who lived a hundred and thirty years, is related to the time of Moses (Il Paral. 24:15). [Questions on the Old and New Testaments, PL 35, — QUESTIONS AND ANSWERS ON GENESIS, Q. 9 (tr. J. Litteral, draft)