I. Gaudium et Spes (#48-50) defines marriage as:
48. The intimate partnership of married life and love has been established by the Creator and qualified by His laws, and is rooted in the jugal covenant of irrevocable personal consent. Hence by that human act whereby spouses mutually bestow and accept each other a relationship arises which by divine will and in the eyes of society too is a lasting one. For the good of the spouses and their off-springs as well as of society, the existence of the sacred bond no longer depends on human decisions alone. For, God Himself is the author of matrimony, endowed as it is with various benefits and purposes. (St. Augustine, De Bene coniugali PL 40, 375-376 and 394, St. Thomas, Summa Theologica, Suppl. Quaest. 49, art. 3 ad 1, Decretum pro Armenis: Denz.-Schoen. 1327; Pius XI, encyclical letter Casti Connubii: AAS 22 (1930, pp. 547-548; Denz.-Schoen. 3703-3714.)All of these have a very decisive bearing on the continuation of the human race, on the personal development and eternal destiny of the individual members of a family, and on the dignity, stability, peace and prosperity of the family itself and of human society as a whole. By their very nature, the institution of matrimony itself and conjugal love are ordained for the procreation and education of children, and find in them their ultimate crown. Thus a man and a woman, who by their compact of conjugal love "are no longer two, but one flesh" (Matt. 19:ff), render mutual help and service to each other through an intimate union of their persons and of their actions. Through this union they experience the meaning of their oneness and attain to it with growing perfection day by day. As a mutual gift of two persons, this intimate union and the good of the children impose total fidelity on the spouses and argue for an unbreakable oneness between them. (Pius XI, encyclical letter Casti Connubii: AAS 22 (1930), pp. 546-547;