CH. III.] EXTERNAL SENSATIONAL ACTIONS. 101 



kinds of external sensations which develope totally distinct 

 sentient actions in the body. 



187. All external sensations are either agreeable or dis- 

 agreeable; and if they be intense, the one is gratification 

 [Kitzel], the other suffering [Schmerz] (80). There is no ex- 

 ternal sensation without these qualities of pleasure or suflfering. 

 (See Baumgarten's 'Metaphysics/ § 481, 405.) Consequently 

 all direct actions of external sensations comprise at the same 

 time those of pleasure and pain, and cannot be separated from 

 them, because one or other is present on every external sen- 

 sation. 



188. All direct sentient actions in the mechanical machines, 

 are efi'ected through the same nerve which produces the ex- 

 ternal material sensation in the brain (129, 131), whether it 

 be the same fibril which received the external impression, or 

 another, in virtue of the sympathy of sentient actions (165, i), 

 or from reflexion (48, iv). But, should the action of an ex- 

 ternal sensation occur in the same machine that received the 

 external impression, the material sensation must necessarily 

 excite in the brain the efferent fibrils of the same nerve which 

 is distributed to the affected mechanical machines as their 

 motor nerve (129, iii). 



189. The difference in the nature of the external impressions 

 on the terminating fibrils of the same nerve, causes the dif- 

 ference between agreeable or disagreeable external sensations. 

 Now, since the external impression is itself an animal moving 

 force of the mechanical machines (182), it follows, that the 

 impression exciting agreeable external sensations, and the 

 impression exciting disagreeable external sensations, can each 

 develope appropriate movements in the mechanical machines. 



190. Since we know nothing of the peculiar nature of an ex- 

 ternal impression, we cannot say wherein it differs when, through 

 the same nerve, it excites in the mind at one time an agreeable, 

 at another a disagreeable external sensation, or when it excites 

 gratification or suffering (40). But since we are no better ac- 

 quainted with the nature of material external sensations in the 

 brain, the only sources of actions in the mechanical machines, 

 dependent on external sensations (55, 129), the resulting move- 

 ments can only be known by observation ; but by this, we are 

 able sufficiently to discriminate between nerve- actions merely 



