The experience of the race, particularly in its movement toward and its progress in civilization, has approved monogamy for the simple reason that monogamy is in harmony with the essential and immutable elements of human nature. Taking the word natural in its full sense, we may unhesitatingly affirm that monogamy is the only natural form of marriage. While promiscuity responds to certain elemental passions and temporarily satisfies certain superficial wants, it contradicts the parental instinct, the welfare of children and of the race, and the overpowering forces of jealousy and individual preference in both men and women. While polyandry satisfied in some measure the temporary and exceptional wants arising from scarcity of food or scarcity of women, it finds an insuperable barrier in male jealousy, in the male sense of proprietorship, and is directly opposed to the welfare of the wife, and fatal to the fecundity of the race. While polygamy has prevailed among so many peoples and over so long a period of history as to suggest that it is in some sense natural, and while it does seem to furnish a means of satisfying the stronger and more frequently recurring desires of the male, it conflicts with the numerical equality of the sexes, with the jealousy, sense of proprietorship, equality, dignity and general welfare of the wife, and with the best interests of the offspring.
In all those regions in which polygamy has existed or still exists, the status of woman is extremely low; she is treated as man's property, not as his companion; her life is invariably one of great hardship, while her moral, spiritual, and intellectual qualities are almost utterly neglected. Even the male human being is in the highest sense of the phrase naturally monogamous. His moral, spiritual, and aesthetic faculties can obtain normal development only when his sexual relations are confined to one woman in the common life and enduring association provided by monogamy. The welfare of the children, and therefore, of the race, obviously demands that the offspring of each pair shall have the undivided attention and care of both their parents. When we speak of the naturalness of any social institution, we necessarily take as our standard, not nature in a superficial or one-sided sense, or in its savage state, or as exemplified in a few individuals or in a single generation, but nature adequately considered, in all its needs and powers, in all the member of the present and of future generations, and as it appears in those tendencies which lead toward its highest development. The verdict of experience and the voice of nature reinforce, consequently, the Christian teaching on the unity of marriage. Moreover, the progress of the race toward monogamy, as well as toward a purer monogamy, during the last two thousand years, owes more to the influence of Christianity than to all other forces combined. Christianity has not only abolished or diminished polyandry and polygamy among the savage and barbarous peoples which it has converted, but it has preserved Europe from the polygamous civilization of Mohammedanism, has kept before the eyes of the more enlightened peoples the ideal of an unadulterated monogamy, and has given to the world its highest conception of the equality that should exist between the two parties in the marriage relation. And its influence on behalf of monogamy has extended, and continues to extend, far beyond the confines of those countries that call themselves Christian.