270 POINTER READINGS 



to place the symbol for carbon (amongst others) in the 

 locality of Mr. X. By similar means I can make an 

 exhaustive physical examination of Mr. X and discover 

 the whole array of symbols to be assigned to his 

 locality. 



Will this array of symbols give me the whole of 

 Mr. X? There is not the least reason to think so. The 

 voice that comes to us over the telephone wire is not the 

 whole of what is at the end of the wire. The scientific 

 linkage is like the telephone wire; it can transmit just 

 what it is constructed to transmit and no more. 



It will be seen that the line of communication has 

 two aspects. It is a chain of inference stretching from 

 the symbols immediately associated with the sensations 

 in my mind to the symbols descriptive of Mr. X; and 

 it is a chain of stimuli in the external world starting 

 from Mr. X and reaching my brain. Ideally the steps 

 of the inference exactly reverse the steps of the physical 

 transmission which brought the information. (Naturally 

 we make many short cuts in inference by applying 

 accumulated experience and knowledge.) Commonly 

 we think of it only in its second aspect as a physical 

 transmission; but because it is also a line of inference 

 it is subject to limitations which we should not necessarily 

 expect a physical transmission to conform to. 



The system of inference employed in physical in- 

 vestigation reduces to mathematical equations governing 

 the symbols, and so long as we adhere to this procedure 

 we are limited to symbols of arithmetical character 

 appropriate to such mathematical equations.* Thus 

 there is no opportunity for acquiring by any physical 



* The solitary exception is, I believe, Dirac's generalisation which 

 introduces g-numbers (p. 210). There is as yet no approach to a general 

 system of inference on a non-numerical basis. 



