“What is this second development? Very simple again. At the base of the brain of every child there is a vacant space during the first twelve or fifteen years. During the age of twelve to fourteen in girls, thirteen to fifteen in boys, this vacant space is slowly filled by a new lobe of the brain and with its growth comes the consciousness of sex and the development of sex powers. “This new nerve center becomes on maturity a powerful physical magnet. The moment this magnet comes into contact with an organization which answers its needs, as certain kinds of food answer the needs of hunger, violent desire is excited. If both these magnets should be equally powerful, the disturbance to both will be great. The longer the personal association is continued the more violent becomes this disturbance, until in highly sensitive natures it develops into an obsession which obscures reason and crushes the will. “The meaning of this impulse is again very simple--the unconscious desire of the male to be a father, of the female to become a mother.” “And there is but one man on earth who could thus affect me?” Mary asked excitedly. “Rubbish! There are thousands.” “Thousands?” “Literally thousands. The reason you never happen to meet them is purely an accident of our poor social organization. Every woman has thousands of true physical mates if she could only meet them. Every man has thousands of true physical mates if he could only meet them. And in every such meeting, if mind and body are in normal condition, the same violent disturbance would result--whether married or single, free or bound. “Marriage therefore is not based merely on the passion of love. It is a crime for any man or woman to marry without love. It is the sheerest insanity to believe that this passion within itself is sufficient to justify marriage. All who marry should love. Many love who should not marry. “The institution of marriage is the great SOCIAL ordinance of the race. Its sanctity and perpetuity are not based on the violence of the passion of love, but something else.” He paused and listened to the call of the quail again from the field. “You hear that bob white calling his mate?” “Yes--and she's answering him now very softly. I can hear them both.” “They have mated this spring to build a home and rear a brood of young. Within six months their babies will all be full grown and next spring a new alignment of lovers will be made. Their marriage lasts during the period of infancy of their offspring. This is Nature's law.