THE TEACHING OF PSYCHOLOGY. 337 



dividual was considered as an absolute whole, sufficient in himself, 

 and having no roots in the past. But the theory might almost be 

 established a priori, for it is certain that heredity plays a j)art in 

 the physical man. Every one recognizes the existence of heredi- 

 tary diseases and the resemblance of children to parents. It is 

 also generally acknowledged that the physical exercises a certain 

 influence over the moral ; it follows, therefore, that what is trans- 

 mitted by the physical may be communicated, in a certain meas- 

 ure, to the moral. Yet much precaution is needed in the interpre- 

 tation of these facts, for the law of heredity has to compete with 

 another psychological law, that of imitation or of contagion by 

 madness, the delusion, and the same delusion, is communicated 

 to another by contagion and not by heredity. Undoubtedly, if 

 the case is one of mother and daughter, it might be maintained 

 that heredity plays a part ; but, in the case of two sisters, there 

 example. It is necessary, therefore, in discussing the facts on 

 which the thesis of psychological heredity is supported, to select 

 those with which it is possible to disengage these two elements 

 from one another. 



The fact of hypnotic suggestion, which has been so much 

 talked of recently that it has nearly become wearisome, is never- 

 theless one of the most certain and best established facts. It 

 causes astonishment solely by the extraordinary consequences 

 which have been seen to be produced by it ; for, at bottom, it was 

 not unknown. It is a familiar fact that there can always be more 

 or less of communication, in normal sleep, between the sleeper 

 and the persons around him. No one is surprised, for example, 

 that when music is performed in the presence of a person who 

 sleeps through it without waking, he will say on waking that 

 during his sleep he attended a concert of angels. The sensation 

 has been entangled with the sleep, and has suggested by association 

 a series of images which have a relation to it. It is known, also, 

 that we can, in some cases, act upon the sleeping man, and obtain 

 responses by speaking, or excite and direct his dreams by some 

 other mark. This elementary fact, exaggerated and developed 

 in certain organizations, and in particular diseases, especially in 

 hysteria, has become the extraordinary fact of suggestion with 

 all its consequences. It is not impossible to find its origin in 

 the normal state. If we tell an infant that the murmuring wind 

 is the voice of a weeper, or that a pale reflection of moonlight 

 is a ghost, it will hear voices and see ghosts. The same fact, in 

 hypnotism and hysteria, produces surprising phenomena. Move- 

 ments, sensations, and more or less complex acts may be suggested 

 to the hypnotized patient. Illusory sensations, and consequently 

 hallucinations, can also be provoked. Like effects can be ob- 

 tained without a real object, and by virtue of speaking alone, or 



70L. XXXIII. — 22 



