But it is palpable, that in so doing we must, year by year, preserve a large percentage of weakly persons, who, marrying freely in their own class, must produce weaklier children, and they weaklier children still. Must, did I say? There are those who are of opinion--and I, after watching and comparing the histories of many families, indeed, of every one with whom I have come in contact for now five-and-thirty years, in town and country, can only fear that their opinion is but too well founded on fact--that in the great majority of cases, in all classes whatsoever, the children are not equal to their parents, nor they, again, to their grandparents of the beginning of the century; and that this degrading process goes on most surely, and most rapidly, in our large towns, and in proportion to the antiquity of those towns, and therefore in proportion to the number of generations during which the degrading influences have been at work. This and cognate dangers have been felt more and more deeply, as the years have rolled on, by students of human society. To ward them off, theory after theory has been put on paper, especially in France, which deserve high praise for their ingenuity, less for their morality, and, I fear, still less for their common-sense. For the theorist in his closet is certain to ignore, as inconvenient to the construction of his Utopia, certain of those broad facts of human nature which every active parish priest, medical man, or poor-law guardian has to face every day of his life. Society and British human nature are what they have become by the indirect influences of long ages, and we can no more reconstruct the one than we can change the other. We can no more mend men by theories than we can by coercion--to which, by the by, almost all these theorists look longingly as their final hope and mainstay. We must teach men to mend their own matters, of their own reason, and their own free-will. We must teach them that they are the arbiters of their own destinies; and, to a fearfully great degree, of their children's destinies after them. We must teach them not merely that they ought to be free, but that they are free, whether they know it or not, for good and for evil. And we must do that in this case, by teaching them sound practical science; the science of physiology, as applied to health. So, and so only, can we check--I do not say stop entirely--though I believe even that to be ideally possible; but at least check the process of degradation which I believe to be surely going on, not merely in these islands, but in every civilised country in the world, in proportion to its civilisation.