460 Additional Notes. 



of producing certain motions in the animal fibre. But if the 

 power of producing fibrous contractions be inherent in this 

 spirit (and such self-operating power is certainly sometimes 

 ascribed by Dr. Darwin to the Spirit of Animation, espe- 

 cially in cases of memory, &rc), then that portion of it which 

 is in immediate contact with the fibre must induce contraction 

 before the application of stimuli, unless the power be counter- 

 acted. But, in this case, nothing is supposed to counteract its 

 action ; and as the effect is not produced, where is the inhe- 

 rent power of this subtle fluid ? If we say that the sensorium 

 does not essentially possess the power, but excites motions of 

 the fibres merely by its own motion, we subject the pheno- 

 mena of life and mind to the principles of mechanics; but it is 

 admitted by Dr. Darwin that the effects bear no mechanical 

 proportion to their causes. 



Further, Dr. Darwin contends that fibrous motions con- 

 stitute our notions or ideas of the qualities of external things. 

 To illustrate this an argument is drawn from the luminous 

 appearance in the eye, when it is struck in the dark, or when 

 a corner of the ball is pressed. This effect, he supposes, 

 is occasioned not by the presence of light, but by mere pres- 

 sure; a supposition which, if admitted, must set aside his 

 theory of ideas. The Sensorial Power in the eye has the 

 same susceptibilities as that in the nerves of touch, and the 

 fibres of both organs are equally contractile. They differ 

 only in the yneans of irritation ; the structure of the external 

 organ of the one being peculiarly adapted to the transmission 

 of light. But if pressure can excite the sensation of a flash, 

 this stimulus is not, like that of light, confined to the eye. 

 It must excite similar fibrous motions of the rete mucosum, 

 and the sense of touch will thus become a medium of vision. 

 But this, though an unavoidable inference from Dr. Dar- 

 win's principles, is contrary to his conclusions. 



Another gross inconsistency appears in the account which 

 this theorist presents of the qualities belonging to Sensorial 

 Power. To say that a substance can assume the property of 

 solidity, and lay it aside; that it can occupy space, and cease 

 to occupy it at pleasure, is to say that it can, at pleasure, 

 exist, and cease to exist. The Sensorial Power is constantly 

 represented as a material substance, at sometimes solid and 

 impenetrable, and at other times not so. Now, if solidity be- 

 long to matter at all, it must be essential to it under every va- 

 riation of form, and can only cease to exist in the destruction 

 of the substance. But this is not the whole of the difficulty: 



