96 HISTORY AND SIGNIFICANCE OF SCIENCE 



In geographical science, to cite further examples, the 

 nature and extent of the earth had become known among the 

 educated and traveled classes. This popular knowledge of 

 geography did not, of course, lead to scientific generaliza- 

 tions, but proved influential along social and political lines. 

 The peoples of western Europe became conscious of their 

 position in the world and of the coexistence of other peoples 

 in all the stages from barbarism to civilization. Foundations 

 were being laid for a science of human society. 



In astronomical science, the nature of the solar system 

 had been ascertained by Copernicus and Galileo and the 

 laws of motion and gravitation had been extended to the 

 heavens by Newton. It remained to set forth the way in 

 which the heavenly bodies had reached then* present form. 

 Cosmic Evolution, with its implication of a dynamic uni- 

 verse, found definite expression in the Nebular Hypothesis 

 of Laplace (1796). 2 By this hypothesis, the laws of mass and 

 motion, as applied by Newton to the present solar system, 

 were extended to the past. The existing system was con- 

 ceived as having reached its present state through the 

 action of natural forces. The nebular hypothesis is not the 

 only theory, of the origin of solar systems, maintained by 

 astronomers at the present day. But the idea of our own and 

 other solar systems as having undergone evolutionary 

 modification, is to-day the accepted historical generalization 

 of astronomy. Laplace and his associates among the 

 French Encyclopaedists believed they were on the threshold 

 of an explanation of the universe in terms of matter and 

 motion. If their generalizations were premature, they were 

 nevertheless in agreement with the explanations since 

 established by science. The concept of cosmic evolution, 

 which the nebular hypothesis implies, is now accepted as a 

 matter of course. 



2 The prevailing statement that the Nebular Hypothesis originated with 

 Kant seems to be incorrect. Lovejoy, A. O., "Kant and Evolution," Popular 

 Scientific Monthly, Dec., 1910. 



