Behold the seven horns of the Lamb, the seven eyes of God — the seven eyes are the seven spirits of the Lamb; seven torches burning before the throne of God seven golden candlesticks, seven young sheep, the seven women in Isaiah, the seven churches in Paul, seven deacons, seven angels, seven trumpets, seven seals to the book, seven periods of seven days with which Pentecost is completed, the seven weeks in Daniel, also the forty-three weeks in Daniel; with Noah, seven of all clean things in the ark; seven revenges of Cain, seven years for a debt to be acquitted, the lamp with seven orifices, seven pillars of wisdom in the house of Solomon.
Now, therefore, you may see that it is being told you of the unerring glory of God in providence; yet, as far as my small capacity shall be able, I will endeavour to set it forth. That He might re-create that Adam by means of the week, and bring aid to His entire creation, was accomplished by the nativity of His Son Jesus Christ our Lord. Who, then, that is taught in the law of God, who that is filled with the Holy Spirit, does not see in his heart, that on the same day on which the dragon seduced Eve, the angel Gabriel brought the glad tidings to the Virgin Mary; that on the same day the Holy Spirit overflowed the Virgin Mary, on which He made light; that on that day He was incarnate in flesh, in which He made the land and water; that on the same day He was put to the breast, on which He made the stars; that on the same day He was circumcised, on which the land and water brought forth their offspring; that on the same day He was incarnated, on which He formed man out of the ground; that on the same day Christ was born, on which He formed man; that on that day He suffered, on which Adam fell; that on the same day He rose again from the dead, on which He created light? He, moreover, consummates His humanity in the number seven: of His nativity, His infancy, His boyhood, His youth, His young-manhood, His mature age, His death. I have also set forth His humanity to the Jews in these manners: since He is hungry, is thirsty; since He gave food and drink; since He walks, and retired; since He slept upon a pillow; since, moreover, He walks upon the stormy seas with His feet, He commands the winds, He cures the sick and restores the lame, He raises the blind by His speech, — see that He declares Himself to them to be the Lord.
The day, as I have above related, is divided into two parts by the number twelve— by the twelve hours of day and night; and by these hours too, months, and years, and seasons, and ages are computed. Therefore, doubtless, there are appointed also twelve angels of the day and twelve angels of the night, in accordance, to wit, with the number of hours. For these are the twenty-four witnesses of the days and nights which sit before the throne of God, having golden crowns on their heads, whom the Apocalypse of John the apostle and evangelist calls elders, for the reason that they are older both than the other angels and than men.
Source: On the Creation of the World (New Advent)