2o6 PHYSICAL BASIS OF CIVILIZATION 



depends, caeteris paribus, on the lengths of the 

 period during which the particles of a mass have 

 exercised their proper motions, and on how much 

 during this period these motions have been free from 

 the hindrance or disturbance above pointed out 

 which arises from the continuous reactions with 

 the universal commotion. Let the reader note in 

 the above the remarkable parallelisms between 

 proper motions and heredity, between the disturb- 

 ance of the tendency to concentration by the uni- 

 versal commotion and variation; also how the 

 relation of each particle and mass to the universal 

 commotion recalls those relations between organisms 

 and their environments which are the basis of 

 natural selection. 



It must now be impressed upon the mind of the 

 reader how the inevitable outcome of the universal 

 commotion, which, as pointed out above, is the 

 broadest possible dictum of all experience, and 

 which, therefore, possesses the highest possible 

 degree of reliability, is exactly identical with the 

 process of evolution as interpreted by Herbert 

 Spencer and other profound leaders of thought. 

 For this outcome is: "A concentration of matter" 

 (like particles concentrating with like) "with 

 concomitant dissipation of motion" (the motion 

 necessarily dissipated in the process of concentration 

 by the like particles is not lost, but imparted by 

 them to the unlike particles, from which they have 

 been dissociated and which carry it off, dissipate it) , 



