142 PHYSIOLOGY. 



but the paroxysms have been continued, a debility is again in- 

 duced which sometimes proves fatal. Any explanation of this 

 debility must be the same as that of the debility induced by ex- 

 ercise, viz. that repeated excitements at length wear out the 

 system. 



" I must add, that the same vigour and debility which affect 

 the whole body, have also effects on the mind in producing the 

 states of courage and timidity. 



" 2. The mobility of the brain (comp. p. 98.) is very different 

 on different occasions ; and will depend, 1. On the various causes 

 of sensibility formerly assigned ; 2. On the state of reflex sensa- 

 tion. Most of our sensations are attended with pleasure or 

 pain ; and considering that these are again the immediate causes 

 of desire and aversion, which, in their different modes, produce 

 all the different states of volition, emotion, and passion, it is suf- 

 ficiently evident how the actions depending upon them will give 

 a greater or less degree of mobility ; 3. Upon the intellectual 

 operations, more purely considered ; 4. Upon the effects of ha- 

 bits, (see CXXIIL). 



" I proceed to consider the symptoms indicating lesions of the 

 intellectual functions or internal senses. I say there are two 

 distinct cases of this, which I mark under the titles offatuitas 

 and delirium. 



" 1. Fatuity is an imbecility of thought and judgment : the 

 sensations are imperfectly excited, and still more imperfectly re- 

 tained ; owing to the first, the relations of bodies are not mark- 

 ed ; owing to the second, they are not recollected ; so that there 

 is a certain weakness in the exercise of thought, judgment, and 

 of the will which depends upon judgment, that is to be distin- 

 guished from an error in these faculties. With regard to this 

 fatuity, we observe, that there exist two different cases of it, the 

 fatuitas infantilis and the fatuitas senilis. As the affection 

 occurs very constantly at these two periods of life, we imagine 

 that it is connected with some peculiar state of the organ at 

 those times. From some observations which show the state of 

 the brain in these cases, we conclude, in general, that the/o- 

 tuitas infantilis depends upon a certain humidity or flaccidity, 

 and the fatuitas senilis upon a certain rigidity of the brain. 



