104 ANIMAL-SENTIENT FORCES. [i. 



all sentient actions of external sensations stimulate the me- 

 chanical machines to which they are extended, either to those 

 movements that are their natural function^ in which case they 

 are sentient actions of agreeable, or at least of neutral sen- 

 sationSj or to those which deviate from their natural function, 

 and these are sentient actions of disagreeable external sensations 

 (191). This applies also to the sentient actions of titillation 

 [Kitzel] and pain [Schmerz], which only differ in degree 

 from the preceding (80). 



196. To understand these views properly, it must be remem- 

 bered, that every pain and every unpleasant external sensation 

 is of itself something contra-natural, and is considered as 

 disease (191), whereas the healthy, that is, the natural condition, 

 is maintained so long as either pleasant or no unpleasant sen- 

 sations are felt. But since effects are as their causes, it follows, 

 that the actions of unpleasant external sensations are contra- 

 natural, while those of pleasant sensations are connatural. All 

 experience supports this view, and since suffering is to be con- 

 sidered as the sentinel of our preservation (184), so also its 

 actions are to be considered as a natural medicine which 

 develops contra-natural changes for the purpose of thereby 

 expelling contra-natural disorders of the organism. 



197. Titillation [Kitzel] is a vivid agreeable external sen- 

 sation (80) ; consequently, its sentient actions render the natural 

 functions of the mechanical machines violent and exaggerated 

 (195, 193). 



198. Pain is a vivid disagreeable external sensation (80); 

 consequently, the mechanical machines are excited by its sentient 

 actions to very violent contra-natural movements (195). 



199. Since a violent and exaggerated natural function of a 

 mechanical machine borders on the contra-natural, the actions 

 from very vivid titillations are nearly allied to pain (197, 198). 

 Consequently, a violent titillation, like pain, often produces 

 convulsive movements. 



200. The mechanical machines to which the nerve that has 

 felt, is distributed, are excited to those movements of which 

 they are capable, in virtue of their structure (193). If the 

 external sensations be agreeable, the movements excited are 

 conformable to the functions of the mechanical machine; if 

 disagreeable, are not conformable (195). 



