IMBECILITY AND LUNACY 467 



that they are persecuting him, or on the other hand, to a belief 

 that they admit his claim to be monarch or deity. 



764. Obviously, then, the difference between the two kinds of 

 insanity is very great. Idiocy is a condition in which there is 

 little or no capacity to learn ; lunacy a condition in which there 

 is capacity to learn but in which there is much ivrong learning. 

 Both kinds of insanity can be imitated in greater or lesser degree 

 by people who are quite capable of normal development. Thus 

 training may so close a man's mind as to render him more or 

 less unable to profit by experience, or it may endow him with 

 strange and what seem to non-believers absurd delusions, as in 

 the case of the adherents of many religions. Feeble-mindedness 

 may arise from injury to the brain at any period of life, and it 

 is not an unusual accompaniment of extreme old age ; but it is 

 seen typically most commonly in people who from birth forwards 

 are more or less incapable of making mental acquirements. On 

 the other hand, lunacy, at any rate clearly marked lunacy, almost 

 invariably manifests itself during or after adolescence. 



765. Probably most alienists will accept my description of 

 lunacy as correct. There is nothing new in it except perhaps the 

 stress laid on memory in the statement that this form of mental 

 defect is due to wrong learning. But the description of feeble- 

 mindedness is new. If it be correct, then, the importance of the 

 part played by memory in human mental development has been 

 as insufficiently realized by alienists as by students of normal 

 psychology. However, when we study their descriptions of the con- 

 dition, we find that simple incapacity to learn is always implied, 

 though, owing to non-recognition of the fundamental truth, other 

 mental states which, on consideration, would be admitted as not 

 especially those of imbecility, are sometimes included. Consider, 

 for example, the following description supplied by the Royal 

 College of Physicians to the Royal Commission on the Care and 

 Control of the Feeble-minded. 



766. " ' Idiots,' i.e. persons so deeply defective in mind from 

 birth or from an early age that they are unable to guard them- 

 selves from common physical dangers, such as, in the case of 

 young children, would prevent their parents leaving them alone. 



" ' Imbeciles,' i.e. persons who are capable of guarding them- 

 selves against common physical dangers, but who are incapable of 

 earning their own living by reason of mental defect from birth or 

 from an early age. 



" * Feeble-minded,' i.e. persons who may be capable of earning a 



