“To sum the matter up: whoever finds himself unsuited to the celibate life should see to it right away that he has something to do and to work at; then let him strike out in God’s name and get married. A young man should marry at the age of twenty at the latest, a young woman at fifteen to eighteen; that’s when they are still in good health and best suited for marriage. Let God worry about how they and their children are to be fed. God makes children; he will surely also feed them. Should he fail to exalt you and them here on earth, then take satisfaction in the fact that he has granted you a Christian marriage, and know that he will exalt you there; and be thankful to him for his gifts and favors.
With all this extolling of married life, however, I have not meant to ascribe to nature a condition of sinlessness. On the contrary, I say that flesh and blood, corrupted through Adam, is conceived and born in sin, as Psalm 51[:5] says. Intercourse is never without sin; but God excuses it by his grace because the estate of marriage is his work, and he preserves in and through the sin all that good which he has implanted and blessed in marriage” (Luther’s Works, v. 45, p. 48).