[1] The natural philosopher Kielmeyer, the teacher of Cuvier, also compared the genital organs with the root, the brain with the arborescence, of a tree. _Cf._ Arthur Schopenhauer, “New Paralipomena” (Grisebach’s edition, p. 217). [2] Eduard von Hartmann points out very effectively that “an assumed love without sensuality is merely a fleshless and bloodless phantom of the creative imagination” (“Philosophy of the Unconscious,” sixth edition, p. 196; Berlin, 1874). CHAPTER I THE ELEMENTARY PHENOMENA OF HUMAN LOVE “_The critical natural philosopher conceives this process, this ‘crown of love,’ in a very matter-of-fact manner, as the process of conjugation of two cells and the coalescence of their nuclei._”--ERNST HAECKEL. CONTENTS OF CHAPTER I The well-spring of love -- The conjugation of the germinal cells as the simplest expression of the nature of the sexes -- The active masculine and the passive feminine principles of sexuality -- Their representation in ancient mythology -- The significance of sexual procreation -- The most important principle of progressive development -- The significance of sexual differentiation -- The development of heterosexuality -- Vestiges of an original hermaphroditic state in men and women -- New acquisitions -- The hymen -- Metchnikoff’s hypothesis of the original significance of the hymen -- The “third sex” -- The attainment of perfection by means of progressive sexual differentiation -- The increase in the intensity of the sexual attractive force in the course of human evolution -- Its cause -- Explanation of Paul Rée -- Theory of Havelock Ellis -- Elementary psychical phenomena of love -- A sensation analogous to one of smell -- Theories of Steffens, Haeckel, and Kröner -- The specific sexual odours of the capryl group -- Odoriferous glands in animals and human beings -- An example from Southern Slavonic folk-lore -- The position of the nose in relation to the genital system -- The sexual rôle of artificial perfumes -- Origin of the latter -- Reduction in size of the organ of smell in the human species -- Primary and secondary elements in human sexuality -- Bölsche’s “fusion-love” and “distance-love” -- Their different significance. CHAPTER I