CH. III.] EXTERNAL SENSATIONAL ACTIONS. 103 



natural or other hinderances (47) . Now, since it is not observed 

 of other conceptions, and of the desires and aversions (which 

 ^come next to external sensations, §§ 68, 89), that they can extend 

 bheir influence to all the mechanical machines supplied with 

 lervesj nay, that the greater number seem to act only in 

 jome, and, indeed, many to act on none (79), it results, that the 

 sphere of the sentient actions from external sensations is the 

 lost extensive of all, and that those mechanical machines supplied 

 dth nerves, which are excited at all by animal- sentient forces, 

 ire capable of certain sentient actions from external sensations. 

 193. The circumstance which is common to all move- 

 Lcnts of mechanical machines, whether they be nerve-actions 

 >nly, or excited by cerebral impressions, or sentient actions 

 [resulting from external sensations, or from other conceptions, 

 jand in which they differ from simply mechanical movements, 

 iis this, — that the stimulus to those movements to which the 

 jmechanical machines in virtue of their structure are adapted, 

 is received through the nerves as an internal or external im- 

 ^pression (31). The movements themselves, would, conse- 

 quently, be the same as those produced by simply mechanical 

 forces, since all movements excited in a machine by whatever 

 force, must necessarily be such as are in accordance with its 

 structure. It follows, therefore, that the circumstance which 

 renders the movement of a mechanical machine in organisms 

 simply animal is, — that it proceeds solely from an unfelt im- 

 pression on the nerve, and not from cerebral impressions caused 

 by conceptions ; that the circumstance which renders the move- 

 ment a sentient action is,— that it is excited by an internal 

 impression arising from conceptions (154); and lastly, that that 

 which constitutes it a sentient action of external sensations 

 is, — that it originates from the internal impression in the 

 brain of external sensations (34, 121). 



194. The more vivid the external sensations are, the more 

 energetic is their action on the mechanical machines, and, 

 therefore, the actions they excite in the latter are vigorous in 

 the same proportion (133). 



195. All movements, of which a mechanical machine is 

 capable in virtue of its structure, are either normal, or in ac- 

 cordance with its natural structure in a state of health, or are 

 abnormal, and opposed to that natural function. Consequently, 



