176 THE THEORY OF SENSATION. 



refer the foniierto the diseased tooth and the latter to the injured limb. 

 I confess my utter inability to come to such a conclusion ; and I feel 

 persuaded that if those who maintain it would, as I have done, expe- 

 riment upon it during a violent attack of tooth-ache, they will find it 

 perfectly impossible to believe the pain to be anywhere but in the 

 organ aifected. My reply to the objection would rather be by an 

 admission of the premises, and a denial of the conclusion — that the 

 pain is indeed felt in the tooth — but that it is the mind there present 

 which feels it. For why should the sensitive principle be shut up 

 into one corner of the sensorium ? B ut more on this subject hereafter. 



Let us refer once more to our definition. We have considered the 

 expression " states of mind ;" let us now notice the qualification given 

 to those states — theyare the immediate sequences of the afl^ectionof the 

 organ. This distinguishes them from all those subsequent judgments 

 which the mind makes respecting external obj ects, and from any intuitive 

 belief which the mind may possess respecting what Berkeley calls out- 

 ness, or something external as causing those sensations. What is 

 tenned perception is hereby excluded from our enquiry, as we have 

 alieady observed. The only remaining expression requiring remark 

 is — " the effects produced by external objects on the organs of sense." 

 We have already assumed the existence of those objects. They in 

 some manner affect the organs of sense. These organs are the 

 external terminations of the nerves. The nerves are ramifications of 

 the medullary substance collected in largest quantity in the cerebrum 

 and cerebellum, there called the brain ; continued in the medulla 

 oblongata, and spinal chord, and thence branching out from between 

 each of the vertebrae in pairs of nerves, the ramifications of which 

 spread over the entire system. The exterior terminations of these 

 nerves form the organs of sense, and it is the effect produced on these 

 organs by foreign substances which we state in our definition to be 

 the immediate antecedents of sensation. 



Briefly summing up what has already been advanced, there is an 

 immaterial substance called mind, which exists in certain states called 

 sensations. There is, also, another substance possessing qualities 

 altogether distinct, called matter. In the matter of the body there 

 is one connected sensorial organ consisting of the brain, spinal mar- 

 row, and neiTes, the external terminations of which, or the organs of 

 sense, are in some manner affected by other material substances 

 extraneous to the body. These bodily affections are the immediate 

 precursors, that is, the physical causes of those mental sensations. 

 Outward material objects, therefore, by medium of the bodily organs, 

 are capable of affecting the immaterial mind. The question now to 

 be examined is — " How is this effect produced ?" 



It will be interesting to examine some of the various replies which 

 have been given to this enquiry. To such examination I now in 

 the second place invite vour attention. 



The great diflSculty with the ancients was to account for the gross 

 objects of matter affecting the spiritual essence, and to meet this they 

 framed the hypotheses, that shadows or phantasms of substances, not 

 substances themselves, were the agents in producing sensation. Plato 



