Marriage 2.4.12

God, who formed Adam from mud, built Eve from a rib and said: “She will be called Life, because she is the mother of all the living” (Genesis 2:7, 22; Genesis 3:20).

From the first naming he showed the task for which she had been prepared, and said: “Increase and multiply and fill the earth” (Genesis 1:28).

Therefore God, the Creator of male and female, formed organs suited to procreation and arranged for bodies to be born from bodies. Yet the power of his action works in their production, governing everything that exists by the same power by which he created it.

If, then, offspring come only through sex, sex only through the body, and the body only through God, who can doubt that fruitfulness is rightly attributed to God?