INTRODUCTION 



In our endeavor to better the conditions of 

 man, probably no facts are more worthy of 

 consideration than those included in his natu- 

 ral history, a science which in its wider aspects 

 has done more in the last few centuries than 

 any other body of knowledge to change our 

 opinion of man's real nature and of his place 

 in the world. How great this change has been 

 will be evident if we compare the ancient view 

 of man's relation to the universe with the 

 opinions of to-day. In early times the heavens 

 were supposed to be a dome from which show- 

 ers descended upon the expanse of earth be- 

 neath, fertilizing it and rendering it a fit abode 

 for man. Here he built habitations, cultivated 

 the soil, and peopled the earth with his off- 

 spring. To him the earth seemed the center 

 of the universe, and he believed that its crea- 

 tion was for his convenience and welfare. 



But this anthropocentric conception was 

 not without its difficulties. Even as early as 

 the days of Aristotle, good reasons were given 

 for the belief that the earth was not a plain 



