INTRODUCTION. 



Laymen in science who wish to follow the trend of modern 

 discovery are limited for the most part to one of two things: 

 Either they must read the pseudo-science of the magazines, 

 which is arranged chiefly for dramatic effect rather than 

 for accurate exposition, or they must turn to specialized 

 and technical works written by the discoverers themselves 

 for their fellow-workers books in which technical training 

 is taken for granted, and the lay reader, however cultured 

 and thoughtful he may be, becomes utterly and hopelessly 

 lost. 



The world is thus divided between men who know and 

 cannot tell, and men who tell and cannot know. The great 

 expositors are dead, Huxley and Tyndall and all the others; 

 and the great expositor of the future, the interpreter of 

 knowledge to the people, has still to be born. The writer 

 of this book, himself, falls under the burden of these difficult 

 conditions. He dares venture the undertaking only be- 

 cause of the need of some interpretation of this new and 

 interesting knowledge and because of his own sincerity. 

 He expects nothing from the reader but a high school 

 education and a love of contemporary natural knowledge. 

 This love of contemporary natural knowledge is legitimate. 

 There is something peculiarly attractive about this border- 

 line between science and ignorance. It is the fighting- 

 line and it is so pre-eminently human and natural to love 

 the spectacle of a struggle. It is the spectacle of a con- 



(xv) 



