There can be no question that as presence has its risks for love, so also has absence.  Absence like presence, in the end, if too prolonged, effaces the memory of love, and absence, further, by the multiplied points of contact with the world which it frequently involves, introduces the problem of jealousy, although, it must be added, it is difficult indeed to secure a degree of association which excludes jealousy or even the opportunities for motives of jealousy.  The problem of jealousy is so fundamental in the art of love that it is necessary at this point to devote to it a brief discussion.

Jealousy is based on fundamental instincts which are visible at the beginning of animal life.  Descartes defined jealousy as “a kind of fear related to a desire to preserve a possession.”  Every impulse of acquisition in the animal world is stimulated into greater activity by the presence of a rival who may snatch beforehand the coveted object.  This seems to be a fundamental fact in the animal world; it has been a life-conserving tendency, for, it has been said, an animal that stood aside while its fellows were gorging themselves with food, and experienced nothing but pure satisfaction in the spectacle, would speedily perish.  But in this fact we have the natural basis of jealousy.[411]

It is in reference to food that this impulse appears first and most conspicuously among animals.  It is a well-known fact that association with other animals induces an animal to eat much more than when kept by himself.  He ceases to eat from hunger but eats, as it has been put, in order to preserve his food from rivals in the only strong box he knows.  The same feeling is transferred among animals to the field of sex.  And further in the relations of dogs and other domesticated animals to their masters the emotion of jealousy is often very keenly marked.[412]

Jealousy is an emotion which is at its maximum among animals, among savages,[413] among children,[414] in the senile, in the degenerate, and very specially in chronic alcoholics.[415] It is worthy of note that the supreme artists and masters of the human heart who have most consummately represented the tragedy of jealousy clearly recognized that it is either atavistic or pathological; Shakespeare made his Othello a barbarian, and Tolstoy made the Pozdnischeff of his Kreutzer Sonata a lunatic.  It is an anti-social emotion, though it has been maintained by some that it has been the cause of chastity and fidelity.  Gesell, for instance, while admitting its anti-social character and accumulating quotations in evidence of the torture and disaster it occasions, seems to think that it still ought to be encouraged in order to foster sexual virtues.  Very decided opinions have been expressed in the opposite sense.  Jealousy, like other shadows, says Ellen Key, belongs only to the dawn and the setting of love, and a man should feel that it is a miracle, and not his right, if the sun stands still at the zenith.[416]