PREFACE. 



difeafes originate in the exuberance, deficiency^ 

 or retrograde a&ion, of the faculties of the fejiforium t 

 as their proximate caiife ; and confift in the difordsred 

 motions of the fibres of the body a as the praxiRWUs e 

 feel: of the exertions of thofe difordered faculties, 



i 



The fenforium polfeffes four diftint powers^ or 

 ties, which are occafionally exerted^ and produce all the 

 motions of the fibrous parts of the body j thcfe are the 

 faculties of producing fibrous motions in ccmfequenee of 

 Irritation, which is excited by external bodies $ in con* 

 fequence of fenfation, which is excited by pleafure or 

 pain ; in confequence of volition, which h excited by de* 

 fire or averfion ; and in confequence of aflbdatioHi 

 which is excited by other fibrous motions, We ar 

 hence fupplied with four natural clafles of difcafes df 

 rived from their proximate caufes j which we ftall term 

 thofe of irritation, thofe of fenfation, thofe of voli 1 

 thofe of affociation, 





