129 May the Father, "of whom all paternity in heaven and earth is named," Who strengthens the weak and gives courage to the pusillanimous and fainthearted; and Christ Our Lord and Redeemer, "the Institutor and Perfecter of the holy sacraments," Who desired marriage to be and made it the mystical image of His own ineffable union with the Church; and the Holy Ghost, Love of God, the Light of hearts and the Strength of the mind, grant that all will perceive, will admit with a ready will, and by the grace of God will put into practice, what We by this letter have expounded concerning the holy Sacrament of Matrimony, the wonderful law and will of God respecting it, the errors and impending dangers, and the remedies with which they can be counteracted, so that that fruitfulness dedicated to God will flourish again vigorously in Christian wedlock.
Source: Casti Connubii (Vatican.va)