We thus realize our full humanity in conjunction with others. In maturity, a man and woman discover the mystery of themselves by uniting in a potentially procreative manner. As mother and child co-experience gestation, parturition, and lactation, they continually rediscover who they are. As husband provides for and protects the more vulnerable members of his family, he, too, realizes his purpose in life. As father and mother share in childrearing responsibilities, they find out what they were designed for, even as they struggle to conform to that high standard. As children take cues from their progenitors to learn what it means to grow from a boy or a girl into a man or a woman, they prepare to complete the cycle, both by returning a favor to their parents in old age and by coupling with a suitable partner to bear the next generation. Just as two persons became one flesh in the beginning, so also each person has an individual identity that nonetheless cannot be removed from its social foundations, nor escape its social responsibilities.

Ryan C. MacPherson, “The Natural Law of the Family,” chapter 11 in Natural Law: A Lutheran Reappraisal, edited by Robert C. Baker (St. Louis: Concordia Publishing House, 2011), 201-19, at 207–8.