328 THE POPULAR SCIENCE MONTHLY 



Long before this, however, at the age of twenty-eight, Darwin had 

 begun his career as a Darwinian. In July, 1837, he began his notes 

 on the transmutation of species, based on purely Baconian principles, 

 on the rigid collection of facts which would bear in any way on the 

 variations of animals and plants under domestication and in nature. 

 Rare as was his reasoning power, his powers of observation were of a 

 still more unique order. He persistently and doggedly followed every 

 clue; he noticed little things which escaped others; he always noted 

 exceptions and at once jotted down facts opposed to his theories. On 

 the voyage the marvelous adaptations of animals and plants had been 

 his greatest puzzle. Fifteen months later, in October, 1838, in read- 

 ing the work of Malthus, on " Population," there flashed across his 

 mind the three-fold clue of the struggle for existence, of constant 

 variabilit}^, and of the selection of variations which happen to be adap- 

 tive. 



The three memorable features of- Darwin's greatest work, " The 

 Origin of Species," are, that he was twenty-one years in preparing it, 

 that, although by 1844 he was a strongly convinced evolutionist and 

 natural selectionist, he kept on with his observations for fifteen years, 

 and the volume even then would have been still longer postponed but 

 for a wonderful coincidence, which constitutes the third and not the 

 least memorable feature. This coincidence was that Wallace had also 

 become an evolutionist and had also discovered the principle of natural 

 selection through the reading of the same essay of Malthus. It is further 

 remarkable that of all persons Wallace selected Darwin as the one to 

 whom to send his paper. It was then through the persuasion of the 

 great botanist Hooker, who had known Darwin's views for thirteen 

 years that these independent discoveries were published jointly on July 

 1, 1858. All the finest points of Darwin's personal character were dis- 

 played at this time; in fact, the entire Darwin- Wallace history up to 

 and including Wallace's noble and self-depreciatory tribute to Darwin 

 on July 1, of last summer, is one of the brightest chapters in the history 

 of science. Wallace himself pointed out the very important distinction 

 that while the theories contained in the two papers published fifty years 

 ago were nearly identical, Wallace had deliberated only three days after 

 coming across the passage in Malthus, while Darwin had deliberated for 

 fifteen years. He modestly declared that the respective credit should be 

 in the ratio of fifteen years to three days. 



Several months past the age of fifty Darwin published his epoch- 

 making work (November, 1859), and despite ill health, between fifty 

 and seventy-three, he produced the nine great volumes which expand 

 and illustrate the views expressed in " The Origin of Species." 



A parallel to this remarkable late productiveness is that of Kant, 

 who also put forth his greatest work after fifty. Let those past the five 



