Both polygamous and polyandric nations and civilisations have gradually receded as far as numerical importance and world prestige go and both institutions are bound to disappear. The development of the human ego, both in men and women, will not permit much longer of the enslavement of one sex to gratify the pleasures of the other. Nor can any group, male or female, enforce its domination over individuals of the opposite sex and make them accept the dogma of an inferior sex by embodying that dogma in any religious creed of the mormon or mohammedan type. =Infidelity.= Plural love is passing but infidelity has taken its place in every possible respect as a sexual and an egotistical form of gratification. When dealing with infidelity we must establish a careful distinction between forms of infidelity due to "normal" causes and other forms due to unconscious complexes. On the other hand we should beware of admitting, as many unscientific writers do, that there is a distinct difference of attitude to infidelity in the two sexes. That shortsighted viewpoint has been unfortunately voiced in hundreds of popular sayings which represent man as the great examplary of infidelity and woman as faithfulness incarnate. Economic conditions, not sexual differences, are at the bottom of the levity with which men treat their heart affairs and of the gravity with which women, officially at least, consider the marriage relationship. Financial dependence and the fear of motherhood compel the domesticated, parasitic type of woman to secure the services of a breadwinner, and after achieving that object, to avoid hurting his susceptibilities. Independent and professional women, especially the sterile or sterilised ones, are frankly "masculine" in their love habits. But I insist on considering certain forms of infidelity as normal and others as abnormal, independently from the question as to whether they are socially desirable or undesirable. The human type which is so perfectly normal that it has no fixation and no definite fetishes, except species fetishes, and which weaklings and puritans designate as "animal," is not likely to be faithful to any mate. Like every strong and healthy animal at rutting time, he or she is sexually aroused by every individual of the opposite sex. No safety complex restrains him as far as sexuality is concerned. The only fears which restrain his search for gratification are fear of exposure and ostracism within his herd, fear of pregnancy or infection and fear of final complications, not to mention of course the fear of inflicting suffering upon a lifemate of whom he may be extremely fond. For we must never forget the fact, unpleasant as it may appear to unscientific hypocrites, that lasting love is a matter of fixation and fetishism, hence, always slightly tainted with neurosis.