98 And how wisely this has been decreed St. Augustine thus shows: "This indeed is fitting, that the lower be subject to the higher, so that he who would have subject to himself whatever is below him, should himself submit to whatever is above him. Acknowledge order, seek peace. Be thou subject to God, and thy flesh subject to thee. What more fitting! What more fair! Thou art subject to the higher and the lower is subject to thee. Do thou serve Him who made thee, so that that which was made for thee may serve thee. For we do not commend this order, namely, 'The flesh to thee and thou to God,' but 'Thou to God, and the flesh to thee.' If, however, thou despisest the subjection of thyself to God, thou shalt never bring about the subjection of the flesh to thyself. If thou dost not obey the Lord, thou shalt be tormented by thy servant." This right ordering on the part of God's wisdom is mentioned by the holy Doctor of the Gentiles, inspired by the Holy Ghost, for in speaking of those ancient philosophers who refused to adore and reverence Him whom they knew to be the Creator of the universe, he says: "Wherefore God gave them up to the desires of their heart, unto uncleanness, to dishonor their own bodies among themselves;" and again: "For this same God delivered them up to shameful affections." And St. James says: "God resisteth the proud and giveth grace to the humble," without which grace, as the same Doctor of the Gentiles reminds us, man cannot subdue the rebellion of his flesh.
Source: Casti Connubii (Vatican.va)