62 SCIENCE (and common sense) 



It is part of the art of the sciences, which has to be picked up in the 

 course of the scientist's training, to recognize the situations in which 

 any particular theory or principle can be appealed to, and when it 

 will cease to hold. 



Nobody today can master all of science because nobody today lives 

 long enough to master the arts of all scientific theories. But he who 

 has mastered a few major theories does thereby come most literally 

 to comprehend certain entire domains of his experience. 



