I'Y 



MENTAL DEFECT AND 

 DEEANGEMENT. 



CHAPTER III. 



GENERAL CONSIDERATIONS. 



THE study of the pathology of mind in the lower animals, of 

 mind in its diseased or disordered states, seems to me to be 

 of great, though yet unacknowledged, importance, because 



1. It throws much light on the physiology of mind, on its 

 normal phenomena. For instance, the presence of imagina- 

 tion in animals is readily inferred from the existence of 

 delusions, which are morbid phenomena. 



2. It rectifies certain popular errors for instance, regard- 

 ing rabies and hydrophobia, by showing that most of the so- 

 called ( madness ' of the lower animals is of a totally different 

 kind, belonging, in fact, to the same category as human 

 ( insanity.' 



3. A study of mind, which regards only its healthy mani- 

 festations, is one-sided and therefore imperfect. 



4. There are many phenomena belonging to the border- 

 land between health and disease that cannot be understood 

 without a due knowledge both of the pathology and physiology 

 of mind. 



5. Health passes into disease so imperceptibly that just 

 as in man what is normal or natural in one species or indi- 

 vidual, may be a significant indication of serious disease in 

 another. 



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