 Marriage is, Aquinas says, a primary human good and, philosophically considered, it has a dual point (end, finis): (i) the procreation and bringing up of children is a manner suited to their good, and (ii) fides, which goes far beyond the literal translation “faithfulness” and includes not only exclusivity and permanence but also the positive readiness and commitment to being united with one’s spouse in mind, body and a mutually assisting domestic life. Aquinas neither subordinates one of these two “ends” to the other, nor regards it as appropriate to choose to divide them. Fides is a good and sufficient reason for engaging in the usus matrimonii, the kind of sexual act that is intended to enable both husband and wife to experience and in a particular way actualize and express the good of their marriage, so that the act’s giving and receiving of delight is token of their commitment.