A sound mental heredity consists essentially in teachability, a capacity to learn the things required by the social order; and the congenital idiot is degenerate by the hereditary factor alone, because he is incapable of learning these things. But a sound heredity is no safeguard against personal degeneracy; if we have teachability all turns upon what is taught, and this depends upon the social environment. The very faculties that lead a child to become good or moral in a good environment may cause him to become criminal in a criminal environment; it is all a question of what he finds to learn. It may be said, then, that of the four possible combinations between good and bad heredity and good and bad environment, three—bad heredity with bad or good environment, and good heredity with bad environment—lead to degeneracy. Only when both elements are favorable can we have a good result. Of course, by bad environment in this connection must be understood bad in its action upon this particular individual, not as judged by some other standard. As the social surroundings of a person can be changed, and his hereditary bias cannot, it is expedient, in that vast majority of cases in which causation is obscure, to assume as a working hypothesis that the social factor is at fault, and to try by altering it to alter the person. This is more and more coming to be done in all intelligent treatment of degeneracy. As a mental trait, marking a person off as, in some sense, worse than others in the same social group, degeneracy appears to consist in some lack in the higher organization of thought. It is not that one has the normal mental outfit plus something additional, called wrong, crime, sin, madness, or the like, but that he is in some way deficient in the mental activity by which sympathy is created and by which all impulses are unified with reference to a general life. The criminal impulses, rage, fear, lust, pride, vanity, covetousness, and so on, are the same in general type as those of the normal person; the main difference is that the criminal lacks, in one way or another, the higher mental organization—a phase of the social organization—to which these impulses should be subordinate. It would not be very difficult to take the seven deadly sins—Pride, Envy, Anger, Sloth, Covetousness, Gluttony, and Lust—and show that each may be regarded as the undisciplined manifestation of a normal or functional tendency. Indeed, as regards anger this was attempted in a previous chapter. “To describe in detail the different varieties of degeneracy that are met with,” says Dr. Maudsley, “would be an endless and barren labor. It would be as tedious as to attempt to describe particularly the exact character of the ruins of each house in a city that had been destroyed by an earthquake: in one place a great part of the house may be left standing, in another place a wall or two, and in another the ruin is so great that scarcely one stone is left upon another.”[105]