There is a consensus of opinion among demographists that this decline is due to the voluntary curtailment of the family in married life. Prudence is the motive, and self-restraint the means by which this curtailment is made possible. But prudence and self-restraint are the characteristic attributes of the best citizens. They are conspicuous by their absence in the worst; and it is a matter of common observation that the hopelessly poor, the drunken and improvident, the criminal and the defective have the largest families, while those in the higher walks of life rejoice in smaller numbers. The very qualities, therefore, that make the social unit a law-abiding and useful citizen, who could and should raise the best progeny for the State, also enable him to limit his family, or escape the responsibility of family life altogether; while, on the other hand, the very qualities which make a man a social burden, a criminal, a pauper, or a drunkard--improvidence and defective inhibition--ensure that his fertility will be unrestrained, except by the checks of biological law. And it now comes about that the good citizen, who curtails his family, has the defective offspring of the bad citizen thrown upon his hands to support; and the humanitarian zeal, born of Christian sentiment, which is at flood-tide to-day, ensures that all the defectives born to the world shall not only be nursed and tended, but shall have the same opportunities of the highest possible fertility enjoyed by their defective progenitors. A higher and nobler human happiness is attainable only through social evolution, and this comes from greater freedom of thought, from bolder enquiry, from broader experience, and from a scientific study of the laws of causation. What "is" becomes "right" from custom, but with our yearnings for a higher ideal, sentiment slowly yields to the logic of comparison, and, often wiping from our eyes the sorrows over vanishing idols, we behold broader vistas of human powers, possibilities, duties, and destiny. As the proper study of mankind is man, influenced wholly by a desire to be useful to a society to which I am indebted for the pleasures of civilised life, I offer this brief volume as a comment on a phase of the social condition of the times, and as my conclusions regarding its interest for the future. * * * * * CHAPTER I. THE PROBLEM STATED.