THK THEORY OF SENSATION*. 173 



ness of the body being thus affected, not the bodily affection itself 

 which I regard as sensation, and which, indeed, the writers referred to 

 regard it to be, however inaccurate the phraseology they employed. 

 But to this point we shall have occasion again to revert. 



As the definition I have given of sensation is itself in substance the 

 only theory I have to offer on the subject, I shall in the first place 

 invite your attention to a consideration of the terms in which it is 

 couched. In regarding sensations as those states of mind imme- 

 diately consequent on the effects produced by external objects on the 

 sensitive organs, we assume the separate existence of mind and of 

 matter. There have not been wanting among philosophers those 

 who have denied this. Some on the one hand have been scep- 

 tical respecting the existence of mind. They would have us believe 

 that thought and feeling are properties of the same substance of 

 which we affinn extension and impenetrability. They would persuade 

 us, not that the mind and body are mysteriously united and wonder- 

 fully dependent on each other, but that there is no mind at all; that the 

 body is itself the mind ; or, that man — observing, reflecting, reason- 

 ing man — is all body. They think they get rid of the difficulties 

 surrounding the subject of the connexion between the spirit and the 

 body, by maintaining that all the operations of what we ignorantly 

 call mind are only the results of a certain condition of the bodily 

 organs, and that our coqioreal system of bones and blood and 

 muscles, which can be felt and weighed — and divided — and grow fat — 

 and become lean, can actually investigate the wonders of science, 

 and follow the mazes of argument — " and build the lofty rhyme" — 

 and love — and hate — and be generous — and experience the joys and 

 the terrors of conscience, and can even worship God. If, then, the 

 body is able to do these gieater things, how much more those that 

 are less ? such as hearing, and tasting, and seeing. Sensation then, 

 according to them, is nothing but the effect of external objects on the 

 body. There is a constant connexion between the sensation and the 

 impression on the organ by the extenial object ; the latter, there- 

 fore, according to them, is the only and the efficient cause of the 

 former — as if invariable antecedence was any proof of efficiency of 

 causation ! As well might we say that the winter causes the spring 

 because it invariably precedes it, or that the day is the cause of night 

 because their connexion is unifonn, as that a certain condition of the 

 organs, because it is the precursor, is also the efficient cause of sen- 

 sation. Such a position is altogether opposed to our consciousness. 

 The operations of mind are felt to be of a kind unattributable to 

 matter. To quote the words of Dr. Reid : — " If one should tell me 

 of a telescope so exactly made as to have the power of seeing ; of a 

 whispering galleiy that had the power of hearing ; of a cabinet, so 

 nicely framed, as to have the power of memory ; or of a machine, so 

 delicate, as to feel pain when it was touched : such absurdities are 

 80 shocking to common sense that they would not find belief even 

 among savages, yet it is the same absurdity to think that the impres- 

 sions of external objects on the machine of our bodies can be the real 

 efficient cause of thought and perception." 



