446 THE BIOC08MOS HISTORICAL. 



* 



try became his laboratory in which he made 

 Life reproduce and reveal its processes, con- 

 firming his views. Still he did not wholly ab- 

 jure the society of his scientific friends whom 

 he could meet in his little trips to London, 

 and who often went to his rural residence, 

 named Down, to see the great naturalist. 



But the chief fact of this second period of 

 Darwin's career is suggested in the following 

 statement: "In July, 1837, I opened my first 

 note-book for facts in relation to the Origin 

 of Species, about which I had long reflected 

 and never ceased working for the next twenty 

 years." Darwin himself thus marks off the 

 foregoing period through which was spun the 

 one thread uniting all his diversified activi- 

 ties : his theory of Evolution. To be sure, he 

 says he had been thinking about it for a long 

 time, especially during his voyage; but it 

 probably lurked as a hidden impulse farther 

 back in his youthful love of Nature which 

 dominated him from childhood. But now he 

 becomes conscious of his life's chief pursuit; 

 he must uncover the origin of species. More- 

 over when he read Malthus fifteen months 

 later (1838) he came upon his basic principle, 

 Natural Selection. 



At last in November, 1859, his pivotal book, 

 yea the pivotal book of the century perhaps 

 more than any other, was published with nu 



