Preface 



effort, a judicial faculty never exceeded among 

 men, served only to confirm his confidence that 

 all the varied forms of life upon earth have come 

 to be what they are through an intelligible pro- 

 cess, mainly by "natural selection." 



The present volume offers from the classic 

 pages of Darwin his summary of the argument 

 of "The Origin of Species," his account of how 

 that book came to be written, and his recapitula- 

 tion of "The Descent of Man. " All this affords 

 a supreme lesson as to the value of observation 

 with a purpose. When Darwin was confronted 

 with an organ or trait which puzzled him, he was 

 wont to ask, What use can it have had ? And 

 always the answer was that every new peculiarity 

 of plant, or beast, is seized upon and held when- 

 ever it confers advantage in the unceasing con- 

 flict for place and food. No hue of scale or 

 plume, no curve of beak or note of song, hut has 

 served a purpose in the plot of life, or advanced 

 the action in a drama where the penalty for fail- 

 ure is extinction. 



As Charles Darwin stood first among the 

 naturalists of the nineteenth century, his advo- 

 cacy of evolution soon wrought conviction 

 among the thinkers competent to follow his 

 evidence and weigh his arguments. The opposi- 

 tion to his theories though short was sharp, and 

 here he found a lieutenant of unflinching courage, 

 of the highest expository power, in Professor 

 Huxley. This great teacher came to America 

 in 1876, and discoursed on the ancestry of the 

 vi 



