412 Additional Notes* 



3. Several of the doctrines which enter into this theory an? 

 not consistent with themselves. Dr. Darwin sometimes uses 

 the word idea to signify the organic affection, and sometimes 

 the mental affection j or, to use his own language. It sometimes 

 denotes ihejibrous motion, and at others the sensorial motion ; 

 that is, it signifies both the cause and the ej^ect. This inac- 

 curate use of an important metaphysical word is the source of 

 much loose, perplexed, and inconsistent reasoning. 



Again J the spirit of animation is said to have the power 

 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, especially 

 in cases of memory, &c,), then that portion of it which is in 

 immediate contact with the fibre must induce contraction be- 

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

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

 action ; and as the eflect 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 i but it is 

 admitted by Dr. Darwin that the effects bear no mechanical 

 proportion to their causes. 



Further, Dr. Darwin contends that fibrous motions constitute 

 our notions or ideas of the qualities of external things. To il- 

 lustrate this an argument is drawn from the luminous appear- 

 ance in the eye, when it is struck in the dark, or when a corner 

 oftheballis pressed. This effect, he supposes, is occasioned 

 not by the presence of light, but by mere pressure 3 a supposi- 

 tion 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 means of irritation ; 

 the structure of the external organ of the one being peculiarly 

 adapted to the transmission of light. But if pressure can ex- 

 cite the sensation of a flash, this stimulus is not, like that of 



