10 Preface to the Ninth Edition 



the preservation of life, he neglected to observe the equally enthu- 

 siastic endeavors of the physicist, the chemist and the engineer to 

 provide means for its destruction. The war has been the rude 

 means of falsifying his delusion and of dispelling his dream of 

 idealism and internationalism. Men of science are like other men! 

 But as these words are being written the world rejoices in an armis- 

 tice that promises peace^a peace longed for and prayed for by 

 hundreds of millions of troubled mortals! One turns his eyes 

 toward the eastern horizon a few days ago reddened by the flames 

 of burning villages and the flashing of the guns, and sees the eternal 

 serenity of a clear, blue sky. May it presage the end of war, a clear 

 understanding among nations and the return of men to useful and 

 creative labor! 



The Author. 

 August, 1 91 9. 



