It is that, owing to profound but intelligible causes, the contrast which necessarily obtains between the sexes in respect of their vital expenditure is most marked in the case of our own species. It is one of the conditions of progress that the young of the higher species make more demands upon their mothers than do the young of humbler forms. In other words, progress in the world of life has always leant upon and been conditioned by motherhood. Thus, as one has so frequently asserted in reference to the modern campaign against infant mortality, the young of the human species are nurtured within the sacred person--the _therefore_ sacred person--of the mother for a longer period in proportion to the body weight than in the case of any other species; and the natural period of maternal feeding is also the longest known. On the other hand, the physical demands made by parenthood upon the male sex are no greater in our case than in that of lower forms; though upon the psychical plane the great fact of increasing paternal care in the right line of progress may never be forgotten. But thus it follows that the law of conservation, asserting that what is spent for self cannot be kept for the race, and that if the demands of the future are to be met the present must be subordinated, not merely applies to woman, but applies to her in unique degree. There are grounds, also, for believing that what is demonstrably and obviously true on the physical plane has its counterpart in the psychical plane; and that, if woman is to remain distinctively woman in mind, character, and temperament, and if, just because she remains or becomes what she was meant to be, she is to find her greatest happiness, she must orient her life towards Life Orient, towards the future and the life of this world to come. Some such doctrines may help us at a later stage to decide whether it be better that a woman should become a mother or a soldier, a nurse or an executioner. CHAPTER V THE DETERMINATION OF SEX We must regard life as essentially female, since there is no choice but to look upon living forms which have no sex as female, and since we know that in many of the lower forms of life there is possible what is called parthenogenesis or virgin-birth. It has, indeed, been ingeniously argued by a distinguished American writer, Professor Lester Ward,[4] that the male sex is to be looked upon as an afterthought, an ancillary contrivance, devised primarily for the advantages of having a second sex--whatever those advantages may exactly be; and secondarily, one would add, becoming useful in adding fatherhood to motherhood upon the psychical plane of post-natal care and education as well.