Any fundamental truth regarding marriage is rendered immeasurably difficult to ascertain because of the immense ranges of variety in human beings, even of the same race, many of which result from the artificial conditions and the unnatural stimuli so prevalent in what we call civilisation. To attempt anything like a serious study of marriage in all its varieties would be a monumental work. Those who have even partially undertaken it have tended to become entangled in a maze of abnormalities, so that the needs of the normal, healthy, romantic person have been overlooked. Each pair, therefore, has tended to repeat the blunders from which it might have been saved, and to stumble blindly in a maze of difficulties which are not the essential heritage of humanity, but are due to the unreasoning folly of our present customs. I have written this book for those who enter marriage normally and healthily, and with optimism and hope. If they learn its lessons they may be saved from some of the pitfalls in which thousands have wrecked their happiness, but they must not think that they will thereby easily attain the perfection of marriage. There are myriad subtleties in the adjustment of any two individuals. Each pair must, using the tenderest and most delicate touches, sound and test each other, learning their way about the intricacies of each other's hearts. Sometimes, with all the knowledge and the best will in the world, two who have married find that they cannot fuse their lives; of this tragedy I have not here anything to say; but ordinary unhappiness would be less frequent than it is were the tenderness of _knowledge_ applied to the problem of mutual adjustment from the first day of marriage. All the deepest and highest forces within us impel us to evolve an ever nobler and tenderer form of life-long monogamy as our social ideal. While the thoughtful and tenderhearted must seek, with ever greater understanding, to ease and comfort those who miss this joyful natural development, reformers in their zeal for side-issues must not forget the main growth of the stock. The beautiful sense for love in the hearts of the young should be encouraged, and they should have access to the knowledge of how to cultivate it, instead of being diverted by the clamour for "freedom" to destroy it. Disillusioned middle age is apt to look upon the material side of the marriage relation, to see its solid surface in the cold, dull light of everyday experience; while youth, irradiated by the glow of its dreams, is unaware how its aerial and celestial phantasies are broken and shattered when unsuspectingly brought up against the hard facts of physical reality. The transmutation of material facts by celestial phantasies is to some extent within the power of humanity, even the imperfect humanity of to-day.