CH. III.] ACTIONS OF IMAGINATIONS. 119 



Now, as the external impression is wanting in the sentient 

 actions of imaginations (228, 229), the co-operation of its vis 

 ^^ervosa is wanting, and, consequently, the movements dependent 

 ^ftpon it do not enter into the sentient actions of imaginations, 

 ^Br, at least, are not excited by it, but occur only incidentally. 

 ^Bf, therefore, an imagination repeats the sub-impressions a, h, c, 

 ^Hf a preceding external sensation, with which certain movements 

 in the mechanical machines are connected, but which are not 

 sentient actions of the external sensations «, h, c, but simply 

 nerve-actions of the co-operating external impression, — these 

 actions do not occur, if the impression itself be not made. 

 Thus, an external impression of food, although not felt, will 

 excite a movement in the bowels as a nerve-action (183), but 

 the imagination of food not actually eaten cannot possibly excite 

 the movement, nor can a mere imagination excite any subor- 

 dinate action resulting as a nerve action from the impression, as, 

 for example, the micturition which follows the taking of food. 



234, i. The sentient actions of imaginations, like those of 

 external sensations, extend to all the mechanical machines 

 which can be moved by external sensations (192, 229), and 

 stimulate them to the same movements, although more feebly 

 and imperfectly ; nay, those connected with imperfect external 

 sensations excite the machines to these movements, with a 

 force almost equal to that of external sensations (232, 229). 



ii. The imaginations of agreeable external sensations (186, 

 228) develope connatural actions (195); those of unpleasant 

 external sensations, contra-natural actions ; those of titillation 

 and pain excite more violent movements (197, 198). 



iii. Just as external sensations do not actually put in motion 

 all the mechanical machines which have nerves to move them 

 (201), so also it is with imaginations (228). 



iv. Just as external sensations, in developing sentient actions, 

 act on the mechanical machines according to the capabilities 

 of each, so is it also with imaginations, and all that has been 

 stated with reference to the former (204-217), applies equally 

 to the latter. 



235. The direct sentient actions of imaginations (hitherto 

 considered exclusively) are often accompanied, in addition to 

 those of true external sensations, and of other imaginations not 

 belonging to them, by incidental actions (219), as those of fore- 



