by luxury, corruption, and other enervating vices, that it undergoes that degeneration of character which prepares and makes easy its overthrow. In like manner a family, reckless of the laws of physical and moral hygiene, may go through a process of degeneracy until it becomes extinct. It was no mere dream of prophetic frenzy that when the fathers have eaten sour grapes the children's teeth are set on edge, nor was it a meaningless menace that the sins of the fathers shall be visited upon the children unto the third and fourth generations; it was an actual insight into the natural law by which degeneracy increases through generations—by which one generation reaps the wrong which its fathers have sown, as its children in turn will reap the wrong which it has sown. What we call insanity or mental derangement is truly, in most cases, a form of human degeneracy, a phase in the working out of it; and, if we were to suffer this degeneracy to take its course unchecked through generations, the natural termination would be sterile idiocy and extinction of the family. A curious despot would find it impossible, were he to make the experiment, to breed and propagate a race of insane people; Nature, unwilling to continue a morbid variety of the human kind, would bring his experiment to an end by the production of sterile idiocy. If man will but make himself the subject of serious scientific study, he shall find that this working out of degeneracy through generations affords him a rational explanation of most of those evil impulses of the heart which he has been content to attribute to the wiles and instigations of the devil; that the evil spirit which has taken possession of the wicked man is often the legacy of parental or ancestral error, misfortune, or wrong-doing. Let me illustrate by an example the nature and bearing of this scientific study.
I will take for this purpose a case which every physician who has had much experience must have been asked some time or other to consider and advise about: a quite young child, which is causing its parents alarm and distress by the precocious display of vicious desires and tendencies of all sorts, that are quite out of keeping with its tender years, and by the utter failure of either precept, or example, or punishment to imbue it with good feeling and with the desire to do right. It may not be notably deficient in intelligence; on the contrary, it may be capable of learning quickly when it likes, and extremely cunning in lying, in stealing, in gratifying other perverse inclinations; and it can not be said not to know right from wrong, since it invariably eschews the right and chooses the wrong, showing an amazing acuteness in escaping detection and the punishment which follows detection. It is, in truth, congenitally conscienceless, by nature destitute of moral sense and actively imbued with an immoral sense. Now, this unfortunate creature is of so tender an age that the theory of satanic agency is not thought to offer an adequate explanation of its evil impulses; in the end everybody who has to do with it feels that it is not responsible for its vicious conduct, perceives that
