258 POINTER READINGS 



mathematics is so closely adapted to the physical con- 

 ceptions. It is not so in all subjects. For example, we 

 may admire the triumph of patience of the mathemati- 

 cian in predicting so closely the positions of the moon, 

 but aesthetically the lunar theory is atrocious; it is 

 obvious that the moon and the mathematician use dif- 

 ferent methods of finding the lunar orbit. But by the 

 use of tensors the mathematical physicist precisely de- 

 scribes the nature of his subject-matter as a schedule of 

 indicator readings; and those accretions of images and 

 conceptions which have no place in physical science are 

 automatically dismissed. 



The recognition that our knowledge of the objects 

 treated in physics consists solely of readings of pointers 

 and other indicators transforms our view of the status 

 of physical knowledge in a fundamental way. Until 

 recently it was taken for granted that we had knowledge 

 of a much more intimate kind of the entities of the ex- 

 ternal world. Let me give an illustration which takes 

 us to the root of the great problem of the relations 

 of matter and spirit. Take the living human brain 

 endowed with mind and thought. Thought is one of the 

 indisputable facts of the world. I know that I think, 

 with a certainty which I cannot attribute to any of my 

 physical knowledge of the world. More hypothetically, 

 but pn fairly plausible evidence, I am convinced that 

 you have minds which think. Here then is a world fact 

 to be investigated. The physicist brings his tools and 

 commences systematic exploration. All that he dis- 

 covers is a collection of atoms and electrons and fields of 

 force arranged in space and time, apparently similar to 

 those found in inorganic objects. He may trace other 

 physical characteristics, energy, temperature, entropy. 

 None of these is identical with thought. He might set 



