Or, to regard the process of evolution in more detail, we find degeneracy or inferiority implied in that idea of variation which is the starting-point of Darwinism. All forms of life, it seems, exhibit variation; that is, the individuals are not quite alike but differ from one another and from the parents in a somewhat random manner, so that some are better adapted to the actual conditions of life, and some worse. The change or development of a species takes place by the cumulative survival and multiplication, generation after generation, of fit or fortunate variations. The very process that produces the fittest evidently implies the existence of the unfit; and the distinctly unfit individuals of any species may be regarded as the degenerate. It will not do to transfer these ideas too crudely to the mental and social life of mankind; but it will hardly be disputed that the character of persons exhibits variations which are partly at least incalculable, and which produce on the one hand leadership and genius and on the other weakness and degeneracy. We probably cannot have the one without having something, at least, of the other, though I believe that the variations of personality are capable, to a great degree, of being brought under rational control. This truth that all forms of deficient humanity have a common philosophical aspect is one reason for giving them some common name, like degeneracy. Another is that the detailed study of fact more and more forces the conclusion that such things as crime, pauperism, idiocy, insanity, and drunkenness have, in great measure, a common causation, and so form, practically, parts of a whole. We see this in the study of heredity, which shows that the transmitted taint commonly manifests itself in several or all of these forms in different generations or individuals of the same family; and we see it in the study of social conditions, in the fact that where these conditions are bad, as in the slums of great cities, all the forms become more prevalent. A third reason for the use of a special term is that it is desirable that the matter receive more dispassionate study than formerly, and this may possibly be promoted by the use of words free, so far as possible, from irrelevant implications. Many of the words in common use, such as badness, wickedness, crime and the like, reflect particular views of the facts, such as the religious view of them as righteousness or sin, and the legal view as criminal or innocent, while degeneracy suggests the disinterestedness of science.