I have already analysed the example of the animal world in my Discourse on Inequality, and on further consideration I think I may refer my readers to that analysis as sufficiently thorough.  I will only add this further point to those already made in that work, that the jealousy which springs from nature depends greatly on sexual power, and that when sexual power is or appears to be boundless, that jealousy is at its height; for then the male, measuring his rights by his needs, can never see another male except as an unwelcome rival.  In such species the females always submit to the first comer, they only belong to the male by right of conquest, and they are the cause of unending strife.

Among the monogamous species, where intercourse seems to give rise to some sort of moral bond, a kind of marriage, the female who belongs by choice to the male on whom she has bestowed herself usually denies herself to all others; and the male, having this preference of affection as a pledge of her fidelity, is less uneasy at the sight of other males and lives more peaceably with them.  Among these species the male shares the care of the little ones; and by one of those touching laws of nature it seems as if the female rewards the father for his love for his children.

Now consider the human species in its primitive simplicity; it is easy to see, from the limited powers of the male, and the moderation of his desires, that nature meant him to be content with one female; this is confirmed by the numerical equality of the two sexes, at any rate in our part of the world; an equality which does not exist in anything like the same degree among those species in which several females are collected around one male.  Though a man does not brood like a pigeon, and though he has no milk to suckle the young, and must in this respect be classed with the quadrupeds, his children are feeble and helpless for so long a time, that mother and children could ill dispense with the father’s affection, and the care which results from it.

All these observations combine to prove that the jealous fury of the males of certain animals proves nothing with regard to man; and the exceptional case of those southern regions were polygamy is the established custom, only confirms the rule, since it is the plurality of wives that gives rise to the tyrannical precautions of the husband, and the consciousness of his own weakness makes the man resort to constraint to evade the laws of nature.

Among ourselves where these same laws are less frequently evaded in this respect, but are more frequently evaded in another and even more detestable manner, jealousy finds its motives in the passions of society rather than in those of primitive instinct.  In most irregular connections the hatred of the lover for his rivals far exceeds his love for his mistress; if he fears a rival in her affections it is the effect of that self-love whose origin I have already traced out,