PROBABILITY AND ENTROPY 155 



circles. Familiarity breeds contempt only for 

 artificiality and pretense; and the law of en- 

 tropy becomes a greater law when limited, as we 

 now must limit it, by the following statement: 

 An isolated system always proceeds in the direc- 

 tion of greater entropy, provided that it be so 

 far removed from the state of equilibrium that 

 the chance fluctuations in that state may be 

 ignored. 



A law of nature becomes a better law when we 

 can predict the exceptions to it. If someone tells 

 YOU that the sun will continue to rise and set 

 through all future time you are not deceived 

 by the finality of this statement. You know that 

 here and there through the galaxy of stars 

 many cataclysms occur which would wipe out 

 whole solar systems. If through a study of the 

 average frequency of such occurrences, or 

 throuo-h a study of the movements of all known 

 bodies in the neighborhood of the sun we pre- 

 dict that the earth will be safe for another tril- 

 lion years, we have far more information than is 

 furnished by the trivial statement that the sun 

 will go on rising for ever. 



And now let me revert once again to the con- 

 cept of time. If 3^ou agree with me that in 

 mechanics, as illustrated by the solar system, 



