Manchester Memoirs, Vol. liv. (1910), No. 14. 13 



in the brain is the physical adjunct of a sensation in the 

 mind, such as visual perception, we may regard the mind's 

 interpretation of the sensation as a transformation of the 

 actual physical process as it would be described by 

 external observers if observed directly by them. 



If now the exact nature of this transformation depends 

 upon the physical process taking place as in the case of 

 the transformations just considered, but at the same time 

 leaves invariant the fundamental laws on which a descrip- 

 tion of the process depends, the description of the process by 

 means of the transformation will be a correct qualitative 

 description but will not be a true quantitative one, since 

 the transformation varies for each independent event and 

 so there are no fixed units of measurement. It is possible 

 that when the mind is concentrated on a subject the type 

 of transformation is practically constant, and so our 

 interpretations of sensations become clearer as they 

 become more of a quantitative nature, but it is dangerous 

 to speculate and so I shall leave the subject at this point. 



