The reproductive instinct, on the other hand, may be thwarted by antagonistic forces—by the selfishness of parents who shun their responsibilities, or of mothers who dread the pains and perils of child-bearing; by the greed of parents who would endow old age rather than foster youth; by the desire of women to enjoy independence rather than seek marriage; by the too early emancipation of children, which leaves to the parents no gains and no joys beyond the cost and trouble of upbringing; by insufficient house-room or exorbitant taxation, or by any one of a thousand causes. Thus the considerations that influence reproduction are infinitely varied, and being of a social character they are neither necessary nor permanent, nor yet universal. They may very well be defeated by motives that belong to the social order, and this is just what happens. And it is at least possible to conceive of a state of society where religious faith has vanished and patriotism is dead, where the family lasts only for one generation, and where all land has been appropriated so that the calling of the father is denied to the son; where existence has again become nomadic and suffering unbearable, and where marriage, easily annulled by divorce, has become more or less of a free union. In such a community, with all incentives to reproduction removed and all antagonistic forces in full operation, the birth-rate would fall to zero. And if all nations have not yet arrived at this stage they all seem to be tending towards it. It is true that a new social environment may give rise to new motives. We believe that it will, but as yet we are ignorant of the nature of these promptings. Paradoxical as it may seem, the sexual instinct plays quite a secondary _rôle_ in the procreation of the human species. Nature doubtless has united the two instincts by giving them the same organs, and those who believe in final causes can admire the ruse which Nature has adopted for securing the preservation of the species by coupling generation with sexual attraction. But man has displayed ingenuity even greater than Nature’s by separating the two functions. He now finds that (since he has known how to get rid of reproduction) he can gratify his lust without being troubled by the consequences. The fears of Malthus have vanished: the other spectre, race suicide, is new casting a gloom over the land.