St. Paul said: "Husbands, love your wives, as Christ loved the Church. . . . This is a great mystery, and I mean in reference to Christ and the Church" (Eph 5:25, 32).
The Sacrament of Matrimony signifies the union of Christ and the Church. It gives spouses the grace to love each other with the love with which Christ has loved his Church; the grace of the sacrament thus perfects the human love of the spouses, strengthens their indissoluble unity, and sanctifies them on the way to eternal life (cf. Council of Trent: DS 1799).
"By its very nature the institution of marriage and married love is ordered to the procreation and education of the offspring and it is in them that it finds its crowning glory." The fruitfulness of conjugal love extends to the fruits of the moral, spiritual, and supernatural life that parents hand on to their children by education. Parents are the principal and first educators of their children.In this sense the fundamental task of marriage and family is to be at the service of life. Spouses to whom God has not granted children can nevertheless have a conjugal life full of meaning, in both human and Christian terms. Their marriage can radiate a fruitfulness of charity, of hospitality, and of sacrifice.
Marriage is based on the consent of the contracting parties, that is, on their will to give themselves, each to the other, mutually and definitively, in order to live a covenant of faithful and fruitful love.