It is often said that the declaration by the Church of the idea of possession by the devil rather encouraged the development of certain mental and nervous states and thus fostered neurotic manifestations of many kinds. This whole question of the possibility of direct diabolic influence over mankind, that is, of some evil spirit deeply influencing certain human beings, is yet a matter that is not nearly so settled as a great many physicians who have not been following scientific work in allied lines seem to think. So distinguished a scientist as Alfred Russel Wallace, the co-discoverer with Darwin of the theory of natural selection, had the feeling that spirits interfered much more in human affairs than a great many people were willing to admit, and that the evil spirits probably could, under certain circumstances, deeply affect individuals. Professor Barrett of Trinity College, Dublin, is even more outspoken in what he has to say in this regard, and now there is a very general feeling among those who have investigated spiritistic phenomena most carefully that if spirits do actually communicate directly with men, it is commonly not the spirits who claim to do the communicating who are actually present. Almost needless to say any such conclusion as this would, {225} if maintained, throw even scientists back to the old idea of diabolism, which the Church, on the strength of many centuries of experience, still teaches. One thing is perfectly sure: that if overzeal on the part of certain ecclesiastics rather encouraged neurotic manifestations because of the alluringly suggestive quality of the thought of diabolic possession, they did no more than physicians did in more modern times by their suggestive methods in the study of hysteria. A great French neurologist of to-day has pointed out that major hysteria as studied by French neurologists of a generation ago has practically disappeared, or occurs very rarely in our day because it is no longer unconsciously suggested to patients by physicians that these major symptoms are being looked for. Overzeal in medicine raised up a whole series of symptoms that had no existence except in the heated imagination of their patients under the influence of strong suggestion. Another extremely interesting phase of this subject is that in the old days many of the sensible ecclesiastics and some of the civil authorities came to recognize that people supposed to be possessed of evil spirits could be cured of their condition not infrequently by roundly whipping them. Sir Thomas More particularly called attention to how much good could be effected in this way. In writing an article on "Psychoneurosis and the War" (International Clinics, Volume II, Series 29) I called attention to this in a paragraph that may be helpful in the understanding of the discussion of diabolic influence.