 The most influential formulation of natural law theory was made by Thomas Aquinas in the thirteenth century. Integrating an Aristotelian approach with Christian theology, Aquinas emphasized the centrality of certain human goods, including marriage and procreation. While Aquinas did not write much about same-sex sexual relations, he did write at length about various sex acts as sins. For Aquinas, sexuality that was within the bounds of marriage and which helped to further what he saw as the distinctive goods of marriage, mainly love, companionship, and legitimate offspring, was permissible, and even good. Aquinas did not argue that procreation was a necessary part of moral or just sex; married couples could enjoy sex without the motive of having children, and sex in marriages where one or both partners is sterile (perhaps because the woman is postmenopausal) is also potentially just (given a motive of expressing love). So far Aquinas’ view actually need not rule out homosexual sex. For example, a Thomist could embrace same-sex marriage, and then apply the same reasoning, simply seeing the couple as a reproductively sterile, yet still fully loving and companionate union.