Paul notes that "For baptized persons, moreover, marriage invests the dignity of a sacramental sign of grace," (Ch. 8). Fourth, marriage mirrors the union of Christ and the Church. The union of marriage should be viewed as a sign and as proof of Christ's love. The characteristics of marriage according to Paul include the following. First, marriage assumes "full human" characteristics by being of "the senses and of the spirit at the same time," (Ch. 9). Marriage and conjugal love permits people to contemplate their role as human beings, and the meaning of being human. The purely physical and mundane features of marriage are thereby elevated to become teaching tools for the soul. Marriage is, in this sense, a uniquely human duty. Conjugal love should be appreciated as a special feature of human life, as a means by which men and women can cultivate a relationship with God and the Church. Although marriage is fundamentally human, marriage is not simply "instinct and sentiment." Marriage furthers loftier goals.

Second, marriage is "principally...an act of the free will," (Ch. 9). Not only is marriage an exercise in free will, but marriage reflects the divine truth of free will. Moreover, marriage should always reflect the free will of both parties. The husband and wife unite on their own volition. Third, marriage is "intended to endure and to grow by means of the joys and sorrows of daily life," (Ch. 9). Life's vicissitudes strengthen the...

Marriage can thus inspire compassion. The "for better or worse" clause in the marriage vow reflects this feature of conjugal love.
Fourth, marriage is a "very special form of personal friendship," characterized by conjugal love (Ch. 9). The special friendship also implies sharing selflessly and ceaselessly of material and intangible goods. Moreover, through their special bond the husband and wife "become one only heart and one only soul," (Ch. 9). Marriage thus approaches the mystical. The bond of conjugal love is unique also in that it enables an individual to attain the perfection of the spirit.

Paul also explicates the two main duties shared between the husband and wife: the duty of fidelity and the duty to procreate. Fidelity is the hallmark of conjugal love. Husband and wife shall remain "faithful and exclusive until death," (Ch. 9). Moral law dictates fidelity absolutely. However, Paul is most concerned with the duty of procreation in the Humanae Vitae. Moral law also dictates procreation absolutely. Birth control must be in accordance with moral law as to interfere with procreation would obstruct God's fecundity. Through procreation, marriage ultimately perpetuates itself for eternity. The primary purpose of a marriage is to bear children and educate them in the religious and moral truths that lead to salvation. Through marriage and only through marriage can the…