In all machines that are supposed to accomplish with little power just as much as those with great power, art must be put in. Consequently, one can already assume that the provision of nature put more art into the organization of the female part than of the male; for it furnished the man with greater power than the woman in order to bring both into the most intimate physical union, which, in so far as they are nevertheless also rational beings, it orders to the end most important to it, the preservation of the species. And moreover, in this quality of theirs (as rational animals), it provided them with social inclinations in order to make their sexual companionship persist in a domestic union.

Two persons convening at random is insufficient for the unity and indissolubility of a union; one partner must yield to the other, and, in turn, one must be superior to the other in some way, in order to be able to rule over or govern him. For in the equality of claims of two people who cannot do without each other, self-love produces nothing but squabbling. In the progress of culture, each partner must be superior in a different way: the man must be superior to the woman through his physical power and courage, while the woman must be superior to the man through her natural talent for mastering his desire for her; on the other hand in still uncivilized conditions superiority is simply on the side of the man.