SELF-PRESERVATION AND THE MENTAL LIFE 145 



legal responsibility and no loss of ability to care for 

 personal interests. Still even these slightest grades 

 of mental disorder are due to cerebral disorder, and 

 their origin cannot be sought in any other direction. 

 When it is said that mental disorders, not associated 

 with demonstrable alterations in the brain, are never- 

 theless of cerebral origin, it is not meant to imply 

 that there are no structural changes in the brain. 

 It is only intended to imply that whatever changes 

 may exist are not demonstrable by our present 

 methods. And that this is no reflection on the 

 science of mental pathology will be quite evident to 

 any one who will take the trouble to consider the 

 unparalleled complexity of the cerebral organization 

 with its uncountable nervous elements, structurally 

 and functionally connected in unthinkably many 

 ways. 



In order to gain some insight into the nature of 

 this supremely important group of mental disturb- 

 ances, it is essential to realize that human beings are 

 born into the world with nervous systems very 

 unequally susceptible to those disorders of the brain 

 for which one cannot at present find a structural 

 basis. While some nervous systems have that in 

 their organization which renders them extremely 

 susceptible to mental disorder, there are others so 

 constituted as to resist successfully within ^limits 

 many of the most common influences that precipi- 

 tate mental disorder. It is only right that, at this 

 point, we should freely admit our complete ignorance 



