=Instinct of Procreation.=--Another irradiation of the male sexual instinct, connected with the preceding, is the instinct of procreation. If there were no other difficulties or consequences, man would without the least doubt be instinctively inclined to copulate with as many women as he could, and procreate as many children as possible. The more he is capable of satisfying his procreative instinct, the more he becomes self-exalted, as he thus sees himself multiplied and feels his power extended by the possession of a great number of wives and children. This is one of the principal causes which urge rich men and polygamous peoples to possess many women. Coitus without object, like that of prostitution, can only assuage the sexual appetite and does not satisfy any of its higher irradiations. It is well known that a happy betrothal, reposing on true love, and not on pecuniary interests, often transforms a young man from pessimism to optimism, from misogyny to philogyny. Skeptics smile at this transformation and regard it as only the transient intoxication of love. This may be true in some cases, but, as we have seen above, when love is ennobled by deep understanding and mutual education, when each knows and respects the other, the transformation remains definite, and is strengthened so much that the honeymoon of the silver wedding is often happier and more exalted than that which followed marriage. We can then say that the optimism created by sexual union cemented by true love rests on the normal accomplishment of the object of life. I cannot too often repeat that work in common, especially social work, on the part of the conjoints, is necessary for their happiness to be complete, and to survive in the one who remains after the decease of the other. =Jealousy.=--The worst irradiation, or rather the worst reaction of contrast of love, which we have inherited from our animal ancestors, and that which is the most deeply rooted, is _jealousy_. Jealousy is a heritage of animals and barbarism; that is what I would say to all those who, in the name of offended honor, would grant it rights and even place it on a pedestal. It is ten times better for a woman to marry an unfaithful than a jealous husband. From the phylogenetic point of view, jealousy originates in the struggle for the possession of woman, at a period when right depended only on brute force. Cunning and violence contended with each other, and when the conqueror was in possession of a female, he had to guard her jealously to prevent her being abducted. Furious combats ensued. As soon as an unaccustomed approach, a look or anything else awakened the least suspicion of the presence of a rival, the male was tormented with a continual and instinctive feeling of defiance and distrust, often increased by the remembrance of the sadness of former defeats and the impotent rage which followed.