“There shall be the great Sabbath which has no evening, which God celebrated among His first works, as it is written, And God rested on the seventh day from all His works which He had made. And God blessedthe seventh day, and sanctified it; because that in it He had rested from all His work which God began to make. Genesis 2:2-3 For we shall ourselves be the seventh day, when we shall be filled and replenished with God’s blessing and sanctification. There shall we be still, and know that He is God; that He is that which we ourselves aspired to be when we fell away from Him, and listened to the voice of the seducer, You shall be as gods, Genesis 3:5 and so abandoned God, who would have made us as gods, not by deserting Him, but by participating in Him. For without Him what have we accomplished, save to perish in His anger? But when we are restored by Him, and perfected with greater grace, we shall have eternal leisure to see that He is God, for we shall be full of Him when He shall be all in all. For even our good works, when they are understood to be rather His than ours, are imputed to us that we may enjoy this Sabbath rest. For if we attribute them to ourselves, they shall be servile; for it is said of the Sabbath, You shall do no servile work in it. Deuteronomy 5:14 Wherefore also it is said by Ezekiel the prophet, And I gave them mySabbaths to be a sign between me and them, that they might know that I am the Lord who sanctify them. Ezekiel 20:12 This knowledge shall be perfected when we shall be perfectly at rest, and shall perfectly know that He is God.
This Sabbath shall appear still more clearly if we count the ages as days, in accordance with the periods of time defined in Scripture, for that period will be found to be the seventh. The first age, as the first day, extends from Adam to the deluge; the second from the deluge to Abraham, equalling the first, not in length of time, but in the number of generations, there being ten in each. From Abraham to the advent of Christ there are, as the evangelist Matthew calculates, three periods, in each of which are fourteen generations—one period from Abraham to David, a second from David to the captivity, a third from the captivity to the birth of Christ in the flesh. There are thus five ages in all. The sixth is now passing, and cannot be measured by any number of generations, as it has been said, It is not for you to know the times, which the Father has put in His own power. Acts 1:7 After this period God shall rest as on the seventh day, when He shall give us (who shall be the seventh day) rest in Himself. But there is not now space to treat of these ages; suffice it to say that the seventh shall be our Sabbath, which shall be brought to a close, not by an evening, but by the Lord’s day, as an eighth and eternal day, consecrated by the resurrection of Christ, and prefiguring theeternal repose not only of the spirit, but also of the body. There we shall rest and see, see and love, love and praise. This is what shall be in the end without end. For what other end do we propose to ourselves than to attain to the kingdom of which there is no end?”
~ St. Augustine of Hippo, The City of God, Book 22, Chapter 30