Existence being such a difficult compromise between our dreams and the material facts of the world, this desire may sometimes be thwarted by factors outside itself; may even be so suppressed as to be invisible in the conduct and unsuspected in the wishes of the lover. Yet the desire to link their lives with the future is deeply woven into the love of all sound and healthy people who love supremely. It is commonly said that most women marry for children, and not out of a personal love, and there is more truth in this saying than is good for the race. To-day, alas, many women cannot find the perfect and sensitive mate their hearts desire and they hope in _any_ marriage to get children which will mitigate the consequent loneliness of their lives. Sometimes they may, to some extent, succeed, but far less often than they imagine, for that strange and still but little understood force “heredity” steps in, and the son of the tolerated father may grow infinitely more like his physical father than he is like the dear delight his mother dreamed he might be. Few girls have not pictured in day dreams the joy of holding in their arms their own beautiful babies. No man of their acquaintance, however, may seem fine enough to be their father. Until she has been crushed by experience, or, unless she listens with absolute belief to the depressing information of her elders, each girl believes that her own intense desire for perfection will be the principal factor in creating the beautiful babies of her dreams. Often it seems as though this power were granted, for women sometimes bear lovely children by fathers in whom one may seek in vain for any bodily grace or charm. The century long working of economic laws based on physical force, the remnants of which still affect us, has resulted in man generally having the selective power and tending to choose for his wife the most beautiful or charming woman that his means allow; hence hitherto on the whole, the race has been bred from the better and more beautiful women. This has undoubtedly tended to keep the standard of physical form from sinking to the utter degradation which we see in the worst of the slums, and in institutions where live the feeble-minded offspring of inferior mothers who have wantonly borne children of fathers devoid of any realization of what they were doing. From these avenues of shame and misery, however, I must steer my line of thought, for this book is written pre-eminently for the young, happy and physically well-conditioned pair who mating beautifully on all the planes of their existence, are living in married love.