xviii INTRODUCTION 



the earth from many of these bodies. Such 

 expanses of space as are implied in these meas- 

 urements were probably never imagined by 

 even the astronomers of olden times and cer- 

 tainly never by those who held the ancient 

 opinion of a flat earth vaulted by the heavens. 

 The immensity of these stretches in relation 

 to the earth and to man brings us to a realiza- 

 tion of our own insignificance. Man is as the 

 merest atom among these magnitudes; and 

 the nations " are counted as the small dust 

 of the balance." 



If, then, the human race can no longer claim 

 the central place in the universe, is not the 

 observed of all observers, what can be said of 

 it? To this question natural science has re- 

 plied that man is the product of his immedi- 

 ate environment. And it therefore behooves 

 those who have his welfare at heart to ac- 

 quaint themselves with this environment as 

 well as with man regarded as one of its prod- 

 ucts. It is the object of these lectures to at- 

 tempt to sketch in outline something of man's 

 nature from this standpoint. 



Viewed near at hand and as a part of his im- 

 mediate surroundings, man has a twofold in- 

 terest. He is, first of all, an incessantly re- 



