CHARLES DARWIN 131 



as a proved fact and adding to it, (4) the facts of heredity 

 and variation, or the general Hkeness, with individual 

 differences, of parents and offspring, we reach the con- 

 clusion, (5) that on the whole those die who are least 

 fitted to maintain their existence — survival of the fittest 

 or natural selection. Again accepting this conclusion 

 as a fact and taking it in conjunction with, (6) the fact 

 that the changes in external conditions are universal 

 and unceasing, the deduction is, (7) that changes of 

 organic forms must take place to keep them in harmony 

 with the changed conditions ; and as the changes of 

 conditions are permanent changes, in the sense of not 

 reverting back to identical previous conditions, the 

 changes of organic forms must be in the same sense 

 permanent and thus originate new species. 



** It is doubtful," writes Huxley, " if any single 

 book, except the Principia [of Newton] ever worked so 

 great and so rapid an evolution in science, or made so 

 deep an impression on the general mind. It aroused a 

 tempest of opposition and met with equally vehement 

 support, and it must be added that no book had been 

 more widely and persistently misunderstood by both 

 friends and foes." 



During his voyage in the Beagle Darwin suffered 

 much from the effects of a serious illness contracted at 

 Valparaiso, and this left its mark upon him to such an 

 extent that, as he tells us in his autobiography, he never 

 really recovered his initial health and strength. " My 

 chief enjoyment and sole employment throughout life," 

 he writes, " has been scientific work, and the excitement 

 from such work makes me, for the time, forget, or drives 

 quite away, my daily discomfort. I have, therefore, 

 nothing to record during the rest of my life, except the 

 pubhcation of my several books." After 1842 Darwin 

 removed from London to a country residence at Down 

 in Kent, where he spent the remainder of his years. 



The first of the books he refers to in the sentence 



