184 CAUSATION OF MENTAL 



individual case of mental disorder in man, than to determine 

 the exact nature or number of its cause or causes. Fre- 

 quentty, if not generally, causation is obscure, uncertain, 

 indirect, not easy of discovery, estimation, determination, or 

 definition. Only exceptionally is it direct, obvious, or 

 demonstrable. 



Superadded to an immediate or exciting cause, there is 

 generally a predisposing or remote one ; and this predisposi- 

 tion itself may be of the most complex structure or nature 

 the accumulated result of qualities both physical and riieiital, 

 inherited from a long ancestry. Moreover, the distinction 

 between predisposing and exciting causes is frequently 

 quite as artificial as that between physical and mental, 

 though both sets of terms are equally convenient expres- 

 sions of provisional opinions, or provisional results of 

 inquiry. What is a predisposing cause in one case, or at 

 one time, may become an exciting cause in or at another, 

 or vice versa. 



The suddenness of the incidence of a cause has also an 

 important bearing on the results producible by that cause. 

 Thus the suddenness of any unusual noise has much to do 

 with the genesis of fear. 



A cause may be external to an animal, and in that case 

 apparent or obvious to man ; or it may be internal and patho- 

 logical, and in this case unintelligible to, or difficult of deter- 

 mination by, human on-lookers, even of a specially educated 

 kind. Causes, however, that are apparently difficult of dis- 

 covery, and that are overlooked even by the veterinarian, are 

 sometimes sufficiently obvious if properly searched for the 

 most familiar instance of which is mania from intestinal 

 worms in the dog (Youatt and Cobbold). 



Naturally a cause may be expected to be operative in 

 proportion as it is prolonged or repeated in other words, in 

 relation to its intensity and duration. This remark applies to 

 all classes of causes, whether they are physical as exposure 

 to cold and heat ; mental as grief or anger ; or mixed as 

 man's cruelty or neglect. 



Thus anger, in its intenser forms of rage or fury, may 

 be really ' a short madness,' as the Koman poet calls it. The 



