CHAPTER II 



THE METHOD 



IN the following discussion several logical 

 principles are used as safeguards against error. 

 They must be formulated so that the reader 

 can determine their validity, or at least grant 

 that I have used a consistent method and have 

 not made haphazard guesses. 



It is a well-accepted principle that mental 

 and physical phenomena are parallel. With- 

 out deciding which is the cause and which 

 the effect, it is easy to see that the presence 

 of a given phenomenon in one field involves 

 some expression of it in the other. The fact 

 of parallelism having been accepted, classifi- 

 cations of differences in the two fields ought 

 to be the same. The actual mental differ- 

 ences must correspond to, and be an expres- 

 sion of, physical differences. So, too, for each 

 physical difference there must be some psychic 

 expression. 



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