Theology of the Body
Blessed John Paul II developed his theology of the body in 129 Wednesday audiences. The talks are also available in The Theology of Marriage and Celibacy: Catechesis on Marriage and Celibacy in the Light of the Resurrection of the Body.
The Two Ends of Marriage
God has given marriage two great purposes: union of husband and wife, and the procreation of and care for children. Each marital act is a renewal of the vows of marriage and is, in that sense, re-creational or, in our current language, recreational.
The two ends are inseparable. One cannot be achieved without the other, nor can one be opposed to the other. Both ends affect how we think about the virtue of chastity in marriage.
The real distinction between them comes into play when considering the sacredness, beauty, meaning, and value of union at a time when the couple know with a very high degree of certitude that they cannot become pregnant through this particular marital act (long-term problems with conception; being in the infertile phase of the monthly cycle; after menopause; sterilized by surgery or side-effects of drugs taken to heal the body; etc.). In such cases, they should act with confidence that their power of union is from God and is pleasing to God, even though they are morally certain that they cannot become pregnant.
In other words, the traditional priority given to the end of procreation does not lead to the absurdity lampooned by Monte Python in one of their more vulgar and anti-Catholic skits. Catholic couples do not have to try to achieve pregnancy every time they unite, nor is their union at such times in any way a "second class" activity.
The two Genesis stories present both ends of marriage. In Genesis 1, the "first commandment" of Torah (according to the count of 613 commandments made by the rabbis) is "be fruitful and multiply." But in Genesis 2, when Adam sees Eve for the first time, the only description given is that "the two become one flesh." No mention is made of procreation in that passage. Similarly, the Song of Songs talks only about the joy of union (and the sorrows that come from disunion), but never mentions procreation as a consequence of union.
The two ends of marriage are married to each other in such a way that both determine the essential nature of marriage. Their union is something like that of the Persons of the Trinity. The Father, Son, and Spirit are one in being (homoousios, consubstantial), but they can be distinguished from each other. As the Athanasian Creed teaches us, one Divine Person is not the same as the other two, but they are inseparable united to each other. The Father is first in a way that the Son and Spirit are not, but the Three Persons are equal in all of God's perfections. The "secondness" of the Son in no way diminishes His glory as God. So, too, the dual ends of marriage are united to each other by God's own design in such a way that the traditional primacy of procreation in no way detracts from the necessity of union. Full union of husband and wife demands openness to "receiving children gladly from God" (one of the essential goods of marriage celebrated in the marriage ceremony); in the natural order, procreation is impossible without the unitive act proper to marriage. They are two sides of a great golden coin.
The unity of husband and wife is essential for the care of children. The intimate joy that they share in private overflows to their whole family and to all who witness their devotion to each other. It is not self-centered or solipsistic. The gift that they enjoy brings blessings to all who see how much they cherish each other.
- Cormac Burke, "Marriage: a personalist or an institutional understanding?". Communio 19 (1992), 278-304.