On the natural law

Why then is sodomy against the natural law? First of all, because man is a species-being and, as we have said, the species to which he belongs-the species that defines his nature-is both rational and social. Men cannot live at all-much less live well-except by the mutual protection and mutual support of other human beings. Morality refers to those rules that mankind has learned, both from reason and experience, are necessary for surviving and prospering. The inclination of many men-what we might call the inclination of their lower nature-to take their sex where they can find it (whether their partners consent to it or not) and ignore the consequences, must be subordinated to their higher nature, which includes the interest of society (and their interest of nature in the species).
Harry Jaffa