114 PSYCHOLOGY. 



with quite as strong an excitement of separate parts as 

 the sensational state comports. So we come back here to 

 our own earlier discrimination between the perceptive and 

 the sensational processes, and to the examples which we 

 gave on pp. 80, 81.* 



HALLUCnSTATIONS. 



Between normal perception and illusion we have seen 

 that there is no break, the process being identically the same 

 in both. The last illusions we considered might fairly be 

 called hallucinations. We must now consider the false 

 perceptions more commonly called by that name.f In or- 



* Here is another good example, taken from Helmholtz's Optics, p. 435: 

 "The sight of a man walking is a familiar spectacle to us. We perceive 

 it as a connected whole, and at most notice the most striking of its pecu- 

 liarities. Strong attention is required, and a .special choice of the point of 

 view, in order to feel the perpendicular and lateral oscillations of such a 

 walking figure. We must choose fitting points or lines in the background 

 with which to compare the positions of its head. But if a distant walking 

 man be looked at through an astronomical telescope (which inverts the 

 object), what a singular hopping and rocking appearance he presents ! No 

 difficulty now in seeing the body's oscillations, and many other details of 

 the gait. . . . But, on the other hand, its total character, whether light or 

 clumsy, dignified or graceful, is harder to perceive than in the upright po- 

 sition." 



f Illusions and hallucinations must both be distinguished from delusions. 

 A delusion is a false opinion about a matter of fact, which need not neces- 

 sarily involve, though it often does involve, false perceptions of sensible 

 things. We may, for example, have religious delusions, medical delusions, 

 delusions about our ow^u importance, about other peoples' characters, etc., 

 ad libitum. The delusions of the insane are apt to affect certain typical 

 forms, often very hard to explain. But in many cases they are certainly 

 theories which the patients invent to account for their abnormal bodily 

 sensations. In other cases they are due to hallucinations of hearing and of 

 sight. Dr. Clouston (Clinical Lectures on Mental Disease, lecture iii ad 

 ^71.) gives the following special delusions as having been found in about 

 a hundred melancholy female patients who were afflicted in this way. 

 There were delusions of 



general persecution; being destitute; 



general suspicion; being followed by the police; 



being poisoned; being very wicked; 



being killed; impending death; 



being conspired against; impending calamity; 



being defrauded; the soul being lost; 



being preached against in church; having no stomach; 



being pregnant; having no inside; 



