SOLUTION OF THE WORLD-PROBLEMS. 375 



by means of a gnome 1,100 years b.c., while Christ 

 himself had no knowledge whatever of astronomy — 

 indeed, he looked out upon heaven and earth, nature 

 and man, from the very narrowest geocentric and 

 anthropocentric point of view. The greatest advance 

 of astronomy is generally, and rightly, said to be the 

 founding of the heliocentric system of Copernicus, 

 whose famous work, De Revolutionibus Orbium 

 Celestium, of itself caused a profound revolution in 

 the minds of thoughtful men. In overthrowing the 

 Ptolemaic system, he destroyed the foundation of the 

 Christian theory, which regarded the earth as the 

 centre of the universe and man as the god-like ruler 

 of the earth. It was natural, therefore, that the 

 Christian clergy, with the Pope at its head, should 

 enter upon a fierce struggle with the invaluable 

 discovery of Copernicus. Yet it soon cleared a path 

 for itself, when Kepler and Galileo grounded it on 

 their true "mechanics of the heavens," and Newton 

 gave it a solid foundation by his theory of gravitation 

 (1686). 



A further great advance, comprehending the entire 

 universe, was the application of the idea of evolution 

 to astronomy. It was done by the youthful Kant in 

 1755 ; in his famous general natural history and 

 theory of the heavens he undertook the discussion, 

 not only of the "constitution," but also of the 

 "mechanical origin " of the whole world-structure on 

 Newtonian principles. The splendid Systeme du 

 Monde of Laplace, who had independently come to 

 the same conclusions as Kant on the world-problem, 

 gave so firm a basis to this new Mecanique Celeste in 

 1796 that it looked as if nothing entirely new of equal 

 importance was left to be discovered in the nineteenth 



