The mystery of sexual love, of this “wonder of life,” from which both religious belief and artistic inspiration have drawn and continue to draw the major part of their force, may ultimately be referred to a single phenomenon in the sexuality of the great group of metazoa to which the major part of the animal world and the human species belong. This process is a conjugation of the female germ cell with the male sperm cell--the “well-spring of love,” to use Haeckel’s expression; in comparison with this conjugation, all other spiritual and physical phenomena, however complicated, are of a subordinate and secondary nature. From this primitive organic process of reciprocal attraction and conjugation of the two reproductive cells has arisen the entire complex of the remaining physical and spiritual phenomena of love. We have, in this process of cell conjugation, a picture in little of love, a greatly simplified representation of the nature of the relations between man and woman; moreover, the highest and the finest psychical experiences and impressions occurring under the influence of love are ultimately no more than the results of this “erotic chemotropism” of the sperm and germ cells. Sexual =differentiation= existed already as a =natural= product in the early stages of organic evolution, and =civilization= has done no more than develop, increase, and refine that differentiation, which is typified in a manner at once simple and convincing--because =directly visible=--in the male sperm cell and the female germ cell. Herein the =specific sexual differences= are made visibly manifest. Procreation results from the approach of the male sperm cell towards the female germ cell, and from the entrance of the former into the latter. Thus, the sperm cell represents the =active=, the germ cell the =passive=, principle in sexuality. Already in this =most important= act in the process of procreation the natural relations between man and woman are very clearly manifested. This fact is clearly grasped already in the mythology and the sepulchral symbolism of antiquity. In these the man is always represented as the active principle; woman, on the contrary, as the passive principle. “Peace reigns in the ovum, but when driven by the desire of creation the masculine god breaks through the shell and begins his work of fertilization, everything at once becomes movement, restless haste, impulsive force, unending circulation. Thus the male generative principle appears as the representative and embodiment of movement in the visible act of creation.... The active principle in Nature appears to be identical with the principle of motion.... Winged is the phallus, quiescent the female; the man is the principle of movement, and the woman the principle of repose; force is the cause of eternal change, woman the picture of eternal repose; for which reason the ‘earth-mother’ is almost always depicted in a sitting posture” (Bachofen).