Thus, among the Eskimo, who practice temporary wife-exchange, Rasmussen states that "a man generally discovers that his own wife is, in spite of all, the best."
"I have always held with the late Professor Laycock," remarks Clouston (Hygiene of Mind, p. 214), "who was a very subtle student of human nature, that a married couple need not be always together to be happy, and that in fact reasonable absences and partings tend towards ultimate and closer union." That the prolongation of passion is only compatible with absence scarcely needs pointing out; as Mary Wollstonecraft long since said (Rights of Woman, original ed., p. 61), it is only in absence or in misfortune that passion is durable. It may be added, however, that in her love-letters to Imlay she wrote: "I have ever declared that two people who mean to live together ought not to be long separated."
"Viewed broadly," says Arnold L. Gesell, in his interesting study of "Jealousy" (American Journal of Psychology, Oct., 1906), "jealousy seems such a necessary psychological accompaniment to biological behavior, amidst competitive struggle, that one is tempted to consider it genetically among the oldest of the emotions, synonymous almost with the will to live, and to make it scarcely less fundamental than fear or anger. In fact, jealousy readily passes into anger, and is itself a brand of fear.... In sociability and mutual aid we see the other side of the shield; but jealousy, however anti-social it may be, retains a function in zoölogical economy: viz., to conserve the individual as against the group. It is Nature's great corrective for the purely social emotions."