Discussion of contraception has been active in the last decade or so; but curiously enough its significance aside from contributing to directly saner ways of life[1] has been little realized. Birth control makes possible such clear-cut distinctions between mating and parenthood that it might be expected to produce radical changes in theories of sex attitude or relationship, forcing the discard of many an argument for personal suppression for the good of children or the honor of the family, and forcing redefinition of concepts of honor and sincerity between the sexes. In such redefinition reciprocity in passion, emotional integrity, and mutual enhancement of life might share in the approval once confined to constancy, fidelity, and duty, virtues that are obviously suggested by the hit or miss system of mating and reproducing our social organization has favored. With little or no self-knowledge or knowledge of men, a girl often marries in order to find out how much she cares or whether or not she qualifies, and then when her experience has but begun she finds herself an expectant mother, and maternity begins to supersede other interests. She may become a parent without the assurance of being well-mated, if not, more tragically, with the certainty of being mismated. Advocates of the monogamous family would do well to consider how essential to an enduring union, at least in our society, experience in love may be, together with restraint from child-bearing before experience is achieved. That neither such considerations nor other changes in the theory of sex morality have yet come to the fore in current discussion is perhaps because the technique of contraception is still in the experimental stage, perhaps because in popular consciousness the morality of contraception in itself is not fully established. How is it going to be established? I doubt if through rationalism or rationalistic propaganda. Social changes, we begin to know, are rarely due to deliberation, in any society. In our society they are due mainly to economic causes. Housing congestion in New York will in time affect birth-control legislation in Albany; and fear of an overpopulated world will drive church as well as state into a new attitude toward multiplying to the glory of God.