There are certain children with respect to whom medical science indicates, beyond the possibility of a doubt, that it is impossible for them ever to become useful members of society; indeed, in the case of many of them, it is obvious that their existence is directly harmful to the species--for example, cripples, high-grade cretins, idiots, and children with gross deformities. But at the present day such children are preserved to lead a life of martyrdom. The greatest possible pains and the highest refinements of medical skill are employed to keep them alive. Huge institutions are erected for their care, and there is great rejoicing if, after years of laborious efforts, some of these small unfortunates have been taught to speak or write a few words. This procedure is a grave infringement of the law of parsimony (see the first paragraph of Chapter V. in the General Part), if only for the reason that in other departments of social life, with the same expenditure of effort, far greater and more valuable results could be obtained. When such children, for one reason or another, find their way into the world, they should be quickly and painlessly destroyed. What method should be adopted to attain this end is a minor consideration. The most suitable plan would appear to be that, after a thorough expert medical examination, such children should be killed by a swift and painless narcotic. For the present, we may leave the question open whether the consent of the parents should first be obtained. According to the moral conceptions of to-day, not only do people shrink back when such energetic measures are proposed, but every act by which individuals, however worthless, are sacrificed in the interests of the species, is regarded as immoral, and even as a punishable offence. But just as to-day we treat certain individuals whose conduct endangers the present generation in such a way as to deprive them of opportunities for doing further harm, so also should we deal as seems best from the social point of view with those individuals who are useless to society, or may be harmful to future generations. As soon as it is generally understood that the interest of future generations is at least as important as that of the present generation, that the interest of the species is more important than that of a few individuals useless to society, and as soon as the number of cases in which such destruction of children is desirable has been greatly diminished owing to the adoption of appropriate preventive measures, it will be regarded as a necessary and moral act to put an end to these defectives.