CHAPTER XXIII 



LAPLACE AND THE STABILITY OF THE 

 SOLAR SYSTEM 



IN the history of intellectual development, more especially in 

 the development of science, precedence among the nations 

 seems to flit about in a lawless way. In the workaday world 

 in which we live, one of the strongest forces is that of heredity ; 

 its workings are revealed not merely among families, but in 

 the larger forms which we may call social, the inheritance from 

 one generation to another of ideas, customs, beliefs. The fact 

 is one of the foundation-stones of the growing science of 

 sociology. 



But genius for discovery, for invention, for the grouping 

 and generalisation of phenomena into broad and simple laws, 

 seems to escape the force of heredity entirely. One would 

 readily think that the career of a great man would mean the 

 impregnation of a generation and a people with his ways of 

 thinking and ways of doing, and that when he had gone there 

 would arise a distinct progeny to carry on his work. But it 

 does not seem to be so. Poland did not become the leader 

 of the intellectual world because of Coppernicus, nor Germany 

 because of Kepler, nor Italy because of Galileo. Newton had 

 no successors among his own people nor in the generation that 

 followed. It was the mathematicians of France who were des- 

 tined in the obscure order of events to take up his work. 



There remained when he died a number of minor but none 

 the less important problems ; subsequent facts, as they came 

 to light, suggested several more. There was one of extreme 

 intricacy which Newton may have pondered but which he never 

 ventured to solve. 



The slow sway of the earth's axis, pointed out by Coppernicus 

 and explained by Newton, was clearly a periodical disturbance. 

 So was the secondary nodding or nutation of the axis discovered 



by Bradley. Their effects might be momentous they might 



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