Additmml Notes. 4 1 3 



light, confined to the eye. It must excite similar fibrous mo- 

 tions of the retc mucosum, and the sense of touch will thus be- 

 come a medium of vision. But this, though u 'unavoidable in- 

 ference from Dr. Darwin's principles, is contrary to his con- 

 clusions. 



Another gross inconsistency appears in the account wlilch 

 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 j that it can occupy space, and ceaae 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 some times solid and impenetrable, 

 and at other times not so. Now, if solidity belong to matter 

 at all, it must be essential to it under every variation of iorm, 

 and can only cease to exist in the destruction of the substance. 

 But this is not the whole of the difficulty : Dr. Darwin tells ut 

 (vol. ii. Additional Notes), that the doctrine of immaterial 

 ideas is a " fanciful hypothesis, like the stories of ghosts and 

 apparitions, which have so long amused the credulous, without 

 any foundation in nature}" yet the sensorial |X)wer is some- 

 times disrobed of its materiality. Is this consistent with the 

 other doctrines concerning the spirit of animation which thii 

 writer teaches? When the sensorial power is led to assume 

 spirituality, it is incapable of being acted upon by matter, as 

 he expressly declares ; consequently it ceases to exist, for it is 

 no longer capable of acting or of being acted uponj and, of 

 course, in all such cases life is suspended or destroyed. We 

 have not, however, yet exposed, in lis full extent, the Incon- 

 sistency of Dr. Darwin on this subject. He observes that, al- 

 though the sensorial power may sometimes disrobe itself of so- 

 lidity ; yet, whenever it communicates motion to the fibres, or 

 is itself excited by their motion, it must necessarily be solid or 

 impenetrable; because, as the muscular fibres approach eacii 

 other in the contraction of a muscle, and as nothing can act 

 where it does not exist, the approach of the partlcU s can be ex- 

 plained only on the supposition of an internieuiate agent. Bu: ii 

 sensorial power, during its exertion, be sulld a:id im])enetrabb. 



