CH. IV.] SUBSTITUTION OF SENTIENT ACTIONS. 301 



that any objection can be raised. If a frog could dream, and 

 dreamed of a pinching of its toe, the imagination would certainly 

 induce it, if not to take a leap, at least to place its limbs in the 

 necessary state of preparation for leaping. Animals endowed 

 with sensational conceptions and instincts afford a thousand 

 proofs of this doctrine, since all their imaginations and fore- 

 seeings express, although imperfectly, the sentient actions of the 

 sensation to which they are related; while many of these actions 

 are at the same time nerve-actions of the external impression 

 which causes the sensation (543, 545). A person dreams that 

 his finger is touching red hot iron, and withdraws his whole 

 arm, as if he really touched it. This retraction is the imper- 

 fect sentient action of the imagined sensation, and may occur 

 as a nerve-action, being analogous to the retraction of its foot 

 by a decapitated frog, when its toe is pinched. Illustrations 

 of this kind could, in fact, be multiplied to any extent in support 

 of the proposition, that the indirect nerve-actions of external 

 impressions are, when the latter are felt, at the same time 

 direct or incidental actions of the sensations of those impressions; 

 and that the feeling itself is nothing superfluous in the pro- 

 duction of these movements, which the impressions themselves 

 can excite as indirect nerve-actions. 



585. The direct nerve-actions of an external impression, or 

 in other words, the movements of irritability (432), can, in 

 general be replaced by sentient actions. Since they take place 

 principally in muscular fibres (445), which are moved by all 

 cerebral forces from external sensations to free-will acts in- 

 clusive, the movements of the muscles are the same, whether 

 they be nerve-actions or sentient actions (161-162); and no 

 result of irritability can be mentioned, which cannot be a 

 sentient action. Innumerable illustrations might be advanced 

 (445_448, 204, 229, &c.) 



586. But since the direct nerve-actions of external impres- 

 sions are developed at the point where the impression is made 

 when it is not transmitted to the brain, or, if transmitted along 

 the nerves, before it reaches the brain — the question arises, 

 whether the impression can produce, when felt, the same direct 

 nerve-actions it produced when unfelt ? This question offers 

 the same difficulties as that mooted in a previous paragraph, 

 regarding indirect nerve-actions. 



