The principal cause of the perennial nature of human love, as contrasted with the periodic character of the sexual impulse of the lower animals, must, as Kant says, be sought in the appearance of these psychical relations between the sexes. Hypotheses such as that put forward by Dr. W. Rheinhard in his book, “Man considered as an Animal Species, and his Impulses,” according to which the prolonged separation of the sexes, consequent on the increased difficulty in the provision of sufficient nutriment (more especially in the Ice Age), led to an incomplete satisfaction of the sexual impulse during the rutting season, and thus gave rise to an enduring sexual excitement, cannot be treated seriously. The same author suggests that the excessive consumption of meat of the Ice Age, owing to the absence of vegetable food, was responsible for the stronger stimulation of the sexual impulse, and for its prolongation beyond the rutting season.
Unquestionably Kant’s explanation is the only true one; it is the one which Schiller had in his mind when in his essay on the connexion between the animal and the spiritual nature of man, he spoke of the happiness of the animals as of such a kind that
“it is dependent merely upon the periods of the organism, and these are subject to chance, to blind hazard, because this happiness rests solely on sensation.”
The sexual love of primitive man was, like this, purely instinctive and impulsive.
For him, beginning, course, and end, of every love-process was “directly linear, with no to-and-fro oscillations into the indefinite province of the transcendental.” The need for love and the satisfaction of that need were in primitive man entirely limited to the physical process of sexual activity (L. Jacobowski, “The Beginnings of Poetry,” p. 84).
It was the interpenetration of the whole of sexuality with spiritual elements which first interrupted this single line of sensation, making in a sense two lines: hence arose the frequently unhappy dualism between body and mind in our experience of love; and yet at the same time it was the cause of the elevation of human love to purely individual feelings, which, extending far beyond the purposes of reproduction, subserved the spiritual demands of the loving individual himself.[6]
Natural science, and especially the doctrine of descent, have shown that in the higher animal world, to which we have proved primitive man belongs, a complication of the sexual impulse exists as compared to this condition in lower forms; this complication consists mainly in the intimate association of sensory stimuli with the sexual impulse. In a speech to monks, reported in the Pali Canon, Buddha has well described the sexual part played by the various senses:
“I do not know, young men, any other form which fetters the heart of man like a woman’s form.
“A woman’s form, young men, fetters the heart of man.
“I do not know, young men, any other voice which fetters the heart of man like the voice of woman.