The Domain of Physical Science 207 



telling them that in that book they would find all that can be known 

 of the ultimate essence of things, and he actually gave them the 

 volume ere his departure. It was carried to Paris and laid before 

 the Academy of Sciences ; but when the old secretary came to 

 open it he saw nothing but blank leaves. ' Ah ! ' said he, ' this is 

 just what I expected.' " 



When the cycle of physical definition is laid bare in this way, 

 we can appreciate the following points. 



Firstly, the avenue leading/ro^ consciousness is blocked. The 

 working definition of our physical entities makes no reference to 

 their value for consciousness ; although that would logically be 

 their most important defining property, since it is because of their 

 contact with consciousness (near or remote) that we recognise 

 them and study them. Theoretical physics substitutes for the 

 actual entities with mental value symbols with no mental value ; 

 and this substitution has often misled us into thinking that the 

 entities of the external world themselves (not the symbols) are of 

 an intrinsic nature independent of consciousness. 



Secondly, working definitions of these entities (or strictly of 

 their symbols) are secured by connecting them one to another in 

 cycles so that there is no loose end projecting into the unknown. 



Thirdly, the avenue is blocked in the direction leading to con- 

 sciousness, for any properties of the entities by which they could 

 interact with consciousness have been dropped from the symbols. 

 The edifice of theoretical physics which has been built up from 

 these symbols can therefore contain nothing capable of interacting 

 with consciousness. In particular, those laws of nature which are 

 implicit in the mode of construction of this edifice cannot be 

 interfered with by human free will. 



Fourthly, the edifice constructed by theoretical physics in the 

 territory secured by this device is by no means trivial. It covers 

 the whole of " field-physics," to which the most conspicuous 

 triumphs of scientific investigation belong. Until recently it was 

 not recognised that field-physics could not cover the whole subject ; 

 and even now those who are convinced that its scope is limited are 

 perhaps in a minority. Professor H, Weyl, a leading authority 

 on Relativity, is prominent in advocating the conclusion that the 

 problems of atomicity and quanta are of a nature which cannot be 

 brought under field-physics ; but his conversion is very recent — 

 as indeed is my own. It is too early to guess whether in this 



