TENDENCIES IN MATHEMATICAL SCIENCE 343 



reasoning, has led us onwards to the remotest regions of heaven, 

 and brought a portion of them within the range of our possibilities ; 

 nay, in our own times so propitious to the extension of knowledge 

 the application of all the elements yielded by the present condi- 

 tions of astronomy has even revealed to the intellectual eyes a heavenly 

 body, and assigned to it its place, orbit, mass, before a single telescope 

 has been directed towards it. Humboldt. 



COSMIC EVOLUTION. Reference has been made to the nebular 

 hypothesis included by Laplace in his extended discussion of the 

 solar system. During the nineteenth century this theory has 

 been subjected to searching scrutiny from many points of view 

 and much doubt has been cast on its validity. 



The following summary of present opinion is given by Hale in 

 his Stellar Evolution : 



The nebular hypothesis of Laplace still remains as the most seri- 

 ous attempt to exhibit the development of the solar system. At- 

 tacked on many grounds, and showing signs of weakness that seem to 

 demand radical modification of Laplace's original ideas, it nevertheless 

 presents a picture of the solar system which has served to connect in 

 a general way a mass of individual phenomena, and to give signifi- 

 cance to apparently isolated facts that offer little of interest with- 

 out the illumination of this governing principle. 



We are now in a position to regard the study of evolution as that 

 of a single great problem, beginning with the origin of the stars in 

 the nebulae and culminating in those difficult and complex sciences 

 that endeavor to account, not merely for the phenomena of life, but 

 for the laws which control a society composed of human beings. 



As a complement to the preceding may be added the following 

 from another specialist in planetary evolution : 



It is to the glory of astronomy that in it were initiated the two 

 most fundamental intellectual movements in the history of mankind, 

 viz. the establishment of the possibility of science and of the doctrine 

 of evolution. Our intellectual ancestors in the valleys of the Euphrates 

 and the Nile and on the hills of Greece looked up into the sky at 

 night and saw order there and not chaos. By painstaking obser- 



