CH. III.] ACTIONS OF IMAGINATIONS. 117 



are wanting, tlie conception of which is necessarily induced by 

 the external impression, and which are not perceived therefore 

 by the soul (68). The material idea, which the external im- 

 pression develops in the brain, consists of more numerous 

 sub-impressions, and is much more perfect, than that which 

 the mind when it repeats it can develope without its assistance. 

 Further, as the imaginations are only imperfect external sen- 

 sations, the material ideas of the imaginative force are only 

 constituents of the material external sensations, which the 

 external impression, by reaching the brain, can alone render 

 perfect and complete. Both are conceptions and material ideas 

 of one and the same kind, but the imaginations are weaker 

 and more imperfect (68). 



229. It may be readily inferred from these views, that the 

 sentient actions of imaginations in the mechanical machines, 

 correspond generally with those of external sensations; that their 

 range of influence is equally extensive ; that they excite similar 

 kinds of movements in the various machines ; and that they 

 are only diff'erent in being somewhat less complete. Experience 

 teaches us the same thing. An imagination excites in the 

 same mechanical machines, the same movements that the 

 previous external sensation developed. An object which causes 

 us to shudder, produces a similar eff'ect when we recall it to 

 recollection; the remembrance of some food that has caused 

 us to vomit, excites vomiting again ; and the recollection of a 

 gratification excites the same conditions of the organs as that 

 in which it was enjoyed. The diff'erence is, that the actions of 

 imaginations are weaker, simpler, and more imperfect than those 

 of external sensations (69). And all this could not be other- 

 wise, since the imaginations produce their material ideas at the 

 cerebral origins of those nerves afifected by those of external 

 sensations (124,67); consequently, the same machines must be 

 put into movement (129, 130), for the same kind of cerebral 

 impression, but more feebly, is made at the origin of the nerves, 

 as by external sensations (67, 228) ; and the resulting movements 

 are similar, but feebler (133). 



230. An entire imagination consists only of some of the 

 elements of a previous external sensation, and, consequently, 

 of only some of their material ideas or impressions on the 

 origins of the nerves. The law, then, of the sentient actions 



