The question now arises: If Love and the higher affections had their origin in the maternal function, how happens it that man, in whom this capacity is absent, and who is devoid, moreover, of an inherent paternal instinct, has come, notwithstanding, to possess these higher affections? One may answer off-hand, with the lightness of the tyro, that these have been transmitted to him by maternal inheritance. But complex biological problems are not thus easily explained. Nature works by processes, not by implications. And the physical functions and the mental attributes of the sexes are so dissimilar, and have, with evolution, so diverged by ever further accentuation, that we must seek for definite biological processes by way of which the male has become endowed with, and whereby his primal characteristics have been transformed by the evolution in him of the maternal instinct--under guise of the wholly new and alien trait of Fatherhood. A study of Evolution shows the differentiation and intensification of Sex-characteristics to have been the main feature in Human advance, and to have been progressively achieved by incalculable centuries of increasing differentiation and intensification of two opposite orders of impulse and faculty. In savages and in all the less civilised races, the personal and temperamental differences between the sexes are but slight, and last for no longer than a few years of life. As with other faculties, Sex-differentiations become ever further intensified and more complexly defined as development rises in the scale. Man becomes more man. Woman, more woman. Most notable during the period over which the human organisation sustains its maximum of condition, these Sex-characteristics take longer to arrive at their perfection, and are longer and more fully sustained in the higher races and organisms than is the case with the lower. Then, with that degeneration of tissue which sets in with on-coming age, the old man becomes womanish, the old woman mannish. It cannot be doubted that human perfection reaches its climax in the accentuation of the differences between the Sex-characteristics, physical and mental, of the one sex from those of the other. The best types of men differ far more from the best types of women than inferior men and women differ from one another. In body and in attribute, the sexes are complementary and supplementary. And their dissimilarities are the measure of their complementary and supplementary values.