LIFE AND WORKS OF DARWIN 327 



observations. At this moment came the third of the great turning 

 points in his life, which as a mysteriously disguised blessing was 

 brought about through ill health. In London he was entering official 

 duties and public scientific service which would undoubtedly have 

 increased and interfered more and more seriously with his work. We 

 can only count it as one of the most fortunate circumstances in the 

 history of science that Darwin at the age of thirty-three was forced to 

 leave London and to move to Down. Here for forty years he never 

 knew for one day the health of an ordinary man; his life was one long 

 struggle against the strain of sickness. But unrealized by him there 

 was the compensation of a mind undisturbed by the constant interrup- 

 tion of outside affairs, such interruption as killed Huxley and is kill- 

 ing so many fine and ambitious men to-day. When I saw Huxley and 

 Darwin side by side in 1879, the one only fifty-four, the other seventy, 

 the younger man looked by far the more careworn of the two. Huxley, 

 the strong man, broke down mentally at fifty-six ; Darwin, the invalid, 

 was vigorous mentally at seventy-two. 



Darwin's writings fall into three grand series. In the nine years 

 after he returned from the voyage, or between his twenty-seventh and 

 thirty-sixth years, Darwin wrote the first series, including his pre- 

 evolutionary geological and zoological works, his " Coral Eeefs " 

 (1842), his "Zoology and Geology of the Voyage of the Beagle" 

 (1844—1846), his "Journal of Researches," the popular narrative of 

 his voyage (1845). Darwin's ill health thereafter shut him off from 

 geology, although his last volume, " The Earthworm," was in a sense 

 geological. 



It is characteristic of the life of every great man that his genius 

 and his ovm self -analysis instinctively guide him to discover his mental 

 needs. 



Until the age of forty-five Darwin in his own opinion had not 

 completed his education, in the sense that education is a broad and 

 exact training. He now proceeded to fill the one gap in his training 

 by devoting the eight years of his life, between thirty-seven and forty- 

 five, to a most laborious research upon the barnacles, or Cirripedia. 

 This gave him the key to the principles of the natural or adaptively 

 branching and divergent arrangement of animals through the laws of 

 descent as set forth in the " Origin," which he certainly could not 

 have secured in any other way. The value he placed on his work on 

 the barnacles is of especial import to-day when systematic work is so 

 liglitly esteemed by many biologists, young and old. Darwin subse- 

 quently, in the words of Hooker, " recognized three stages in his 

 career as a biologist, the mere collector at Cambridge, the collector 

 and observer on the Beagle, and for some years afterwards, and the 

 trained naturalist after, and only after, the Cirripede work." 



