And if these new observations upon the nature of femaleness were not enough to warn the writer who should rashly propose, after the fashion of the unwise, who on every hand lay down the law on this matter, to state once and for all exactly what, and what only, every woman should be, we find that another long-held belief as to the relative variety of men and women has lately been found baseless. It was long held, and is still generally believed--in consequence of that universal confusion between the effects of nature and of nurture to which we have already referred--that women are less variable than men, that they vary within much narrower limits, and that the bias towards the typical, or mean, or average, is markedly greater in the case of women than of men. A vast amount of idle evidence is quoted in favour of a proposition which seems to have some _a priori_ plausibility. It is said--of course, without any allusion to nurture, education, environment, opportunity--that such extreme variations as we call genius are much commoner amongst men than women: and then that the male sex also furnishes an undue proportion of the insane--as if there were no unequal incidence of alcohol and syphilis, the great factors of insanity, upon the two sexes. Nevertheless, observant members of either sex will either contradict one another on this point according to their particular opportunities, or will, on further inquiry, agree that women vary surely no less generally than men, at any rate within considerable limits, whatever may be the facts of colossal genius. Indeed, we begin to perceive that differences in external appearance, which no one supposes to be less general among women than among men, merely reflect internal differences; and that, as our faces differ, so do ourselves, every individual of either sex being, in fact, not merely a peculiar variety, but the solitary example of that variety--in short, unique. The analysis of the individual now being made by experimental biology lends abundant support to this view of the higher forms of life--the more abundant, the higher the form. So vast, as yet quite incalculably vast, is the number of factors of the individual, and such are the laws of their transmission in the germ-cells, that the mere mathematical chances of a second identical throw, so to speak, resulting in a second individual like any other, are practically infinitely small. The greater physiological complexity of woman, as compared with man, lends especial force to the argument in her case. The remarkable phenomena of "identical twins," who alone of human beings are substantially identical, lend great support to this proposition of the uniqueness of every individual: for we find that this unexampled identity depends upon the fact that the single cell from which every individual is developed, having divided into two, was at that stage actually separated into two independent cells, thus producing