Scope and Purport of Evolution 57 



cumference with which it is concentric. Motion 

 is never transformed into thought, but only into 

 some other form of measurable (in fact, or at 

 any rate in theory, measurable) motion that takes 

 place in nerve-threads and ganglia. It is not the 

 thought, but the nerve-action that accompanies the 

 thought, that is really " transformed motion" I 

 say that if we are going to verify the theory of 

 correlation, it must be done (actually or theoreti- 

 cally) by measurement; quantitative equivalence 

 must be proved at every step ; and hence we must 

 not change our unit of measurement ; from first to 

 last it must be a unit of motion : if we change it for 

 a moment, our theory of correlation that moment 

 collapses. I say, therefore, that the theory of cor- 

 relation and equivalence of forces lends no support 

 whatever to materialism. On the contrary, its 

 manifest implication is that psychical life cannot 

 be a mere product of temporary collocations of 

 matter. 



The argument here set forth is my own. When 

 I first used it, I had never met with it anywhere in 

 books or conversation. Whether it has since been 

 employed by other writers I do not know, for dur- 

 ing the past fifteen years I have read very few 

 books on such subjects. At all events, it is an 

 argument for which I am ready to bear the full 



