CCC 1664
Christian Mystery›SECTION TWO THE SEVEN SACRAMENTS OF THE CHURCH›CHAPTER THREE THE SACRAMENTS AT THE SERVICE OF COMMUNION›IN BRIEF
Unity, indissolubility, and openness to fertility are essential to marriage. Polygamy is incompatible with the unity of marriage; divorce separates what God has joined together; the refusal of fertility turns married life away from its "supreme gift," the child (GS 50 # 1).