PREFACE ix 



are changed, and I shall not be suspected of 

 levity if I treat with occasional whimsicality 

 some of the most serious questions that arise 

 from our study of the world of nature. 



I have endeavored not to be painful and yet 

 to be careful. Although I am chiefly addressing 

 a popular audience, nowhere have I concealed 

 difficulties nor have I wittingly sacrificed accu- 

 racy of thought. Indeed I am in part address- 

 ing the specialist too, and hope that he may find 

 in the several chapters something new of sub- 

 stance or method. 



It would be the height of presumption to 

 claim that anything like a System of Philoso- 

 phy is contained in these simple essays, which 

 have been brought by the publishers to the 

 dimensions of a book only by generous spacing 

 between the lines. And yet, reading between 

 these lines, the reader may perhaps discern the 

 outlines of a singularly satisfying little philoso- 

 phy, which I venture to believe is shared by a 

 number of men of science, although it differs 

 as widely from the materialism traditionally 

 attributed to scientists as it does from the thinly 

 disguised theology of classical metaphysics. 



Berkeley, California, 

 July U, 1926. 



