SPASMODIC AFFECTIONS. 4j 



ment ; but the remarkable difference that occurs in seemingly 

 like causes producing tetanus, gives some doubt on this sub- 

 ject. 



MCCCVII. Having now enumerated the occasional causes of 

 epilepsy, I proceed to consider the predisponent. As so many 

 of the above-mentioned causes act upon certain persons, and not 

 at all upon others, there must be supposed in those persons a 

 predisposition to this disease. But in what this predisposition 

 consists, is not to be easily ascertained. 



" Now I do not say that epilepsy always depends on a pre- 

 disponent cause. There are causes sufficiently powerful to ex- 

 cite it in every person, and in every kind of constitution, but 

 the existence of a predisponent cause is more commonly prob- 

 able." 



MCCCVIII. As many of the occasional causes are weak 

 impressions, and are applied to most persons with little or no ef- 

 fect, I conclude, that the persons affected by those causes are 

 more easily moved than others ; and therefore that, in this case, 

 a certain mobility gives the predisposition. It will, perhaps, 

 'make this matter clearer, to show, in the first place, that there 

 is a greater mobility of constitution in some persons than in 

 others. 



MCCCIX. This mobility appears most clearly in the state 

 of the mind. If a person is readily elated by hope, and as 

 readily depressed by fear, and passes easily and quickly from the 

 one state to the other ; . if he is easily pleased, and prone to gai- 

 ety, and as easily provoked to anger, and rendered peevish ; if 

 liable, from slight impressions, to strong emotions, but tenacious 

 of none ; this is the boyish temperament, qui colligit ac ponit 

 iram temere, et mutatur in horas ; this is the varium et mu- 

 tabile fcemina ; and, both in the boy and woman, every one 

 perceives and acknowledges a mobility of mind. But this is 

 necessarily connected with an analogous state of the brain ; that, 

 is, with a mobility in respect of every impression, and therefore 

 liable to a ready alternation of excitement and collapse, and of 

 both to a considerable degree. 



MCCCX. There is, therefore, in certain persons, a mobility 

 )f constitution, generally derived from the state of original sta- 

 lina, and more exquisite at a certain period of life than at others ; 



