8 In the creation God finished His works in six days, and rested on the seventh. The history of the world contains six periods marked by the dealings of God with men. The first period is from Adam to Noah; the second, from Noah to Abraham; the third, from Abraham to David; the fourth, from David to the captivity in Babylon; the fifth, from the captivity to the advent of lowliness of our Lord Jesus Christ; the sixth is now in progress, and will end in the coming of the exalted Saviour to judgment.
What answers to the seventh day is the rest of the saints—not in this life, but in another, where the rich man saw Lazarus at rest while he was tormented in hell; where there is no evening, because there is no decay. On the sixth day, in Genesis, man is formed after the image of God; in the sixth period of the world there is the clear discovery of our transformation in the renewing of our mind, according to the image of Him who created us, as the apostle says. As a wife was made for Adam from his side while he slept, the Church becomes the property of her dying Saviour, by the sacrament of the blood which flowed from His side after His death.
The woman made out of her husband's side is called Eve, or Life, and the mother of living beings; and the Lord says in the Gospel: "Except a man eat my flesh and drink my blood, he has no life in him." The whole narrative of Genesis, in the most minute details, is a prophecy of Christ and of the Church with reference either to the good Christians or to the bad. There is a significance in the words of the apostle when he calls Adam "the figure of Him that was to come;" and when he says, "A man shall leave his father and mother, and shall cleave to his wife, and they two shall be one flesh.
This is a great mystery; but I speak concerning Christ and the Church." This points most obviously to the way in which Christ left His Father; for "though He was in the form of God, and thought it not robbery to be equal with God, He emptied Himself, and took upon Him the form of a servant." And so, too, He left His mother, the synagogue of the Jews which cleaved to the carnality of the Old Testament, and was united to the Church His holy bride, that in the peace of the New Testament they two might be one flesh. For though with the Father He was God, by whom we were made, He became in the flesh partaker of our nature, that we might become the body of which He is the head.
Source: Reply to Faustus the Manichaean (New Advent)