The science of eugenics teaches that nature is stronger than nurture. The characters of any living being are determined by two factors, heredity and environment, or nature and nurture, but inheritance is more vital than environment. Heredity and education supply a potential figure, both multiplied give something, if one is nothing the result is nothing. But heredity is the weightier factor.[CH] When nature and nurture compete for supremacy on equal terms, says Galton, the former proves the stronger. Neither is self-sufficient; the highest natural endowments may be starved by defective nurture, while no carefulness of nurture can overcome the evil tendencies of an intrinsically bad physique, weak brain or brutal disposition. No degenerate or feeble stock can ever be converted into a healthy and sound stock by environment, such as sanitary surroundings, good laws, education, wealth, etc., as the radical doctrinaires would like to make us believe. Such means may render individual members of the stock passable or even strong members of society, but the same process will have to be gone through again and again with their offspring. Improved conditions of life mean better health for the existing population, greater educational facilities mean greater capacity for using existing ability. But lasting improvement can only be secured by breeding from good stock. The development of the future generations will be little influenced by environmental improvements, if the conditions of the blood have been neglected. Nothing can be brought out from a child by euthenics which is not within him. The elimination of the feeble stock, met with not only in the slums but also in the quarters of wealth, which weighs down the body politic, can only be effected by the prevention of the propagation of those afflicted with undesirable characters.