It is, of course, conceivable that these two halves of the biological unit might have been made, or might have developed, alike in everything except the sexual function. At least they might have been as much alike as men are alike. They might have been of the same size, possessed of the same strength, of the same figures and gestures, complexion and hair. Their voices might have been alike. They might have had the same kinds of nervous systems, with the same desires, feelings, ideas and tendencies. In the assertions and arguments born of intellectual, industrial, social and political readjustments, it is often assumed that this is the case. Differences are minimized or denied, and an attempt is made to resolve the world of men and women into a world of human beings capable of living together in mingled competitions and cooperations, regardless of sex, except where the reproductive process is considered. But this view is superficial; born of argument it breaks down when confronted by any body of significant facts. Again, it has happened that in the long struggle of developing civilization, sometimes one and sometimes the other sex has gained what has seemed an advantage over the other, just as in the development of any man's individual life, his brain may gain a seeming advantage over his stomach, so that it has more than its fair share of nourishment and activity. Arguing from such a case, we might declare the brain superior to the stomach in power, health and function; but in the long accounting, all such temporary superiorities are wiped out. So with men and women, seeming advantages for either are gained only at the expense of the common life; and in the last analysis, each finds his individual value only in the common life of the unit. Let us try then to see what the special characteristics of women are, ignoring as far as possible the accidental variations of individuals, and the temporary advantages or disadvantages due to economic or ideational forces, and all assertions of what would be if things were not as they are. While the whole matter of sex differences is in a state of unsettlement, it seems very certain that males are more active and more variable than females. This superabundant vitality appears in the males of the higher animals in secondary sex characteristics, such as more abundant and unnecessary hair and feathers, tusks, spurs, antlers, wattles, brilliant colors and scent pouches. It also appears in mating calls, songs, and general carriage of the body. Correspondingly, the female is smaller, duller colored, and less immediately attractive than the male.