From the constitution on the Church in the modern world of The Second Vatican Council
The sanctity of marriage and the family
Husband and wife, by the covenant of marriage, are no longer… two, but one flesh. By their intimate union of persons and of actions they give mutual help and service to each other, experience the meaning of their unity, and gain an ever deeper understanding of it day by day.
This intimate union in the mutual self-giving of two persons, as well as the good of the children, demands full fidelity from both, and an indissoluble unity between them.
Christ the Lord has abundantly blessed this richly complex love which springs from the divine source of love and is founded on the model of his union with the Church.
In earlier times God met his people in a covenant of love and fidelity. So now the Savior of mankind, the Bridegroom of the Church, meets Christian husbands and wives in the sacrament of matrimony. Further, he remains with them in order that, as he loved the Church and gave himself up for her, so husband and wife may, in mutual self-giving, love each other with perpetual fidelity.
True married love is caught up into God’s love; it is guided and enriched by the redeeming power of Christ and the saving action of the Church, in order that the partners may be effectively led to God and receive help and strength in the sublime responsibility of parenthood.
Christian partners are therefore strengthened, and as it were consecrated, by a special sacrament for the duties and the dignity of their state. By the power of this sacrament they fulfill their obligations to each other and to their family and are filled with the spirit of Christ. This spirit pervades their whole lives with faith, hope and love. Thus they promote their own perfection and each other’s sanctification, and so contribute together to the greater glory of God.
Hence, with parents leading the way by example and family prayer, their children – indeed, all within the family circle – will find it easier to make progress in natural virtues, in salvation and in holiness. Husband and wife, raised to the dignity and the responsibility of parenthood, will be zealous in fulfilling their task as educators, especially in the sphere of religious education, a task that is primarily their own.
Children, as active members of the family, contribute in their own way to the holiness of their parents. With the love of grateful hearts, with loving respect and trust, they will return the generosity of their parents and will stand by them as true sons and daughters when they meet with hardship and the loneliness of old age.
Taken from the second reading in today’s Office of readings of the Liturgy of Hours from http://www.divineoffice.org