BIOLOGICAL FOUNDATIONS OF SOCIOLOGY 553
which selection formerly eliminated are tending to become more common. The huge brain of man is a very complex and delicate machine. A defect (an unfavorable variation) in any of its parts is apt to throw the whole out of gear ; and, like other variations, such a defect, such a predisposition to insanity, tends to be inherited. Unless, therefore, we find means to check the output of children by the mentally unsound, the insane will multiply until the state is no longer able to bear the weight of their main- tenance. Selective breeding in this case is a dire necessity, and, therefore, a certainty in the near future.
As I understand him, Mr. Galton proposes to exalt our race by encouraging the finest types to have large families. I venture to suggest, instead, that, for the present at least, we shall limit our efforts to discouraging the multiplication of the most unfor- tunate types. The latter proceeding would be more practicable, since, as regards mind at least, the feeble types are more easily detected than the best, and since it is always more easy to stop a horse drinking than to make him drink. But, as a fact, both Mr. Galton's suggestion and my own are utterly impracticable in the present state of public opinion, and even, if I may say, of public intelligence. Before the one proposal or the other can be thought of as anything more than a mere subject for academic discussion, we must have a more enlightened public, a wider diffusion of the knowledge of the laws of heredity. Of sheer necessity, that diffusion of knowledge will come ere long. I think I know the path it will follow. The medical profession com- prises the largest and, if united, the most powerful body of scien- tific men in the world. At present no systematic instruction in heredity is given to its members. Presently that will be changed. The doctor will realize that other things and more things are known about heredity than he supposes. He will recognize that the science is not summed up by the hypothesis that, if a man con- tracts a disease or is drunken, his offspring will tend to be sickly or insane. He will perceive that the facts of heredity are just as essentially and naturally a part of his medical equipment as the facts of physiology and anatomy. At present he is in no way distinguished intellectually above his contemporaries of the same
