118 ANIMAL-SENTIENT FORCES. [i. 



of imaginations in the mechanical machines, is this: — whatever 

 portions of the elements of a preceding entire (225) external 

 sensation are contained in an imagination, the sentient actions 

 of those elements are repeated, although feebly, in the same 

 mechanical machines (229, 106.) 



231. Since many elements of an entire external sensation 

 may consist of subordinate external sensations, and an imagination 

 therefrom be made up principally or wholly of the latter (228, 

 225), it follows, that an imagination may produce few or none 

 of the sentient actions of the original sensation, but principally 

 or solely those of the subordinate (230). Certain food formerly 

 taken excited spasm of the stomach ; this cramp caused a new 

 pain, — a subordinate external sensation (225), from which 

 general convulsions arose, or subordinate sentient actions. 

 Now when this food is brought to the recollection, convulsions 

 are immediately excited, but without the gastric spasm being 

 excited also. In this case the imagination excites only the 

 subordinate sentient actions of the antecedent primary external 

 sensation, passing over the primary sentient actions. 



232. Although the absence of the external impression is the 

 cause why the sentient actions of imaginations are less perfect 

 and more feeble than those of external sensations, yet strong 

 imaginations can cause imperfect external sensations which 

 imitate the action of external impressions on the nerves (148); 

 and so imaginations, accompanied by imperfect external sensa- 

 tions, may develope such perfect and vigorous sentient actions, 

 that they can hardly be distinguished from those of real external 

 sensations (229, 150). Thus, an insane person, or one that 

 dreams, or any individual with a vivid imagination, imagines he 

 has swallowed an active purgative, and is purged in consequence; 

 or vomits from dreaming of taking nauseous food, &c. 



233. i. A mere external impression can excite no imagination 

 if it be not felt ; consequently its nerve-action, as such, is never 

 at any time a sentient action of an imagination, if it be not the 

 sentient action of its sensation (228, 184, i). But such a nerve- 

 action may be felt and therefore imagined, and this imagination 

 can have sentient actions in the mechanical machines. 



ii. The external impressions often excite by its own vis 

 nervosa (7) those movements which are sentient actions of the 

 external sensation, in which case they are nerve actions (183). 



