INTRODUCTION 



main, to a passage in the cited chapter of Spen- 

 cer where the latter (in the editions of the " First 

 Principles" previous , to the last) explicitly 

 declares that : " The law of metamorphosis, 

 which holds among the physical forces, holds 

 equally between them and the mental forces. 

 Those modes of the Unknowable which we 

 call motion, heat, light, chemical affinity, etc., 

 are alike transformable into each other, and into 

 those modes of the Unknowable which we dis- 

 tinguish as sensation, emotion, thought ; these, 

 in their turns, being directly or indirectly re- 

 transformable into the original shapes. That 

 no idea or feeling arises, save as a result of some 

 physical force expended in producing it, is fast 

 becoming a commonplace of science." Fiske's 

 mode of expression is deliberately different 

 from this one. Citing substantially the same 

 facts as Spencer, Fiske draws the conclusion 

 that " there is no such thing as a change in 

 consciousness which has not for its correlative 

 a chemical change in nervous tissue." This 

 correlative, however, is not said by Fiske to be 

 transformed into the change of consciousness, 

 but to accompany it and to correspond to it. 

 We shall see later how Fiske insists upon the 

 view, mentioned in passing in the present chap- 

 ter, that " the gulf between the phenomena of 

 consciousness and all other phenomena is an 

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