In nature, the consummation of the physical act of union between lovers generally results in the conception of a new life. We share this physical aspect of mating and the resulting parenthood with most of the woodland creatures. How far many of the lowlier lives are conscious of the future results of their mating unions is a problem in elementary psychology beyond the realm of present knowledge. But that parenthood is the natural result of their union is to-day known, one must suppose, by almost all young couples who wed. I am still uncertain how far the two are _conscious_ of this in the early days of their union, when every circumstance encourages that supreme self-centredness of happy youth. Much must depend on the age, and on the previous experience and education of the two; much also on their relative natures. A profoundly introspective and thoughtful man and woman are more liable than others to be speedily aware of the many interwoven strands of their joint lives, and to live consciously on several planes of existence simultaneously. The supreme act of physical union as I have shown in my book, _Married Love_, consists fundamentally of three essential and widely differing reactions, having effects in correspondingly different regions. There is (_a_) the intimately personal effect on the internal secretions and general vitality of the individual partaking of that sacrament; (_b_) there is the social effect of the union of the two in a mutual act in which they must so perfectly blend and harmonize; and (_c_) there is the racial result which may lead to the procreation of a new life. In the early days of the honeymoon, personal passion and the concentrated delight of each in the mate is probably more than sufficient in all its rich complexity to fill the consciousness of the two who are thus united in a life-long comradeship to form that highest unit, the pair. But as education and the conscious control of our lives grow, the young pair who are so blissfully self-centred as not to remember or not to be aware of the racial effects of their acts are probably decreasing in numbers. Among the best of those who marry to-day, the majority only enter upon parenthood or the possibility of parenthood when they feel justified in so doing. The young man who profoundly loves his wife and who considers the future benefit of their child, protects her from accidental conception or from becoming a mother at times when the strain upon her would be too great, or when he is unable to give her and the coming child the necessary care and support. That myriads of children are born without this consideration on the part of their parents applies to the commonalty of mankind, but not to the best.