Lactantius, Divine Institutes 7.14

Since we have spoken of the soul's immortality, we must now teach to what extent and when that gift is granted to humanity, so that those who imagine certain mortals were made gods by mortal decrees and judgments may see their own perversity and folly exposed here as well — whether because they discovered arts, taught the use of certain crops, bestowed useful gifts for human life, or slaughtered savage beasts. How far such merits fall short of immortality we have shown in the earlier books and will show again now, so that it becomes clear that justice alone begets eternal life for man, and God alone bestows the reward of eternal life. For those who are said to have become immortals by their own merits — since neither justice nor any true virtue dwelt in them — did not win immortality for themselves, but death through sins and lusts; they earned not a heavenly reward but infernal punishments, which hang over them and over all who worshiped them. I will demonstrate that the time of this judgment is drawing near, so that a worthy recompense may be paid to the just and a deserved penalty inflicted on the impious.

Plato and many other philosophers, ignorant of the origin of things and of the supreme moment when the world was made, declared that many thousands of ages had elapsed since this most beautiful ordering of the world came into being — perhaps following the Chaldeans, who, as Cicero reports in the first book of On Divination, delude themselves by claiming to possess records embracing 470,000 years. Because they thought they could never be called to account, they believed themselves free to lie. But we, whom the divine scriptures instruct in the knowledge of truth, know both the beginning and the end of the world. We will now treat the end at the close of this work, since we explained the beginning in the second book. Let the philosophers who count thousands of ages from the world's beginning understand that the sixth millennium has not yet run its course. When that number is complete, the consummation must come and the condition of human affairs be reformed for the better. The argument for this must be set forth first, so that the reason may shine forth.

God completed this admirable work of nature, the world, in the space of six days, as the secrets of sacred scripture contain it, and hallowed the seventh day on which he rested from his labors. This is the Sabbath day, which in Hebrew takes its name from the number, and from this the number seven is legitimate and full. There are seven days by which the orbits are completed in their turn, seven stars that never set, and seven planets called wandering, whose unequal courses and motions are believed to produce the varieties of things and times. Therefore, since all God's works were perfected in six days, the world must remain in this present state for six ages — that is, six thousand years. For the great day of God is bounded by a circle of a thousand years, as the prophet declares: "Before your eyes, Lord, a thousand years are like one day" (Psalm 90:4). And just as God labored during those six days in fashioning so many things, so his religion and truth must labor through these six thousand years while malice prevails and dominates. And again, because he rested on the seventh day after perfecting his works and blessed it, at the close of the sixth millennium all malice must be abolished from the earth, and justice must reign for a thousand years, with tranquility and rest from the labors the world has long endured. How this will come to pass I will explain in due order.

We have often said that lesser and fleeting things are figures and foreshadowings of greater things, so that this present day of ours — bounded by the sun's rising and setting — bears the image of the great day, which is determined by a circuit of a thousand years. In the same way the figure of the earthly man prefigured the formation of the heavenly people. For just as God, after completing all things made for man's use, fashioned man himself on the sixth day and led him into this world as into a house already carefully prepared, so now on the sixth great day the true man is fashioned by the Word of God — that is, the holy people are formed by God's doctrine and precepts unto righteousness. And just as then a mortal and imperfect man was formed from the earth to live a thousand years in this world, so now the perfect man is fashioned from this earthly age, that, vivified by God, he may rule in this same world for a thousand years. But how the future consummation will be, and what outcome awaits human affairs, anyone who searches the divine letters will discover. The voices of secular prophets, harmonious with the heavenly ones, also announce the end of things and the downfall after a brief time, describing as it were the final old age of a weary and decaying world. Whatever the prophets and seers declare will happen before that final consummation arrives, I will gather from all sources and link together.