MODERN SCIENCE. 139 



was absolutely necessary because the question touched not 

 heavenly bodies, not the earth's history, about which ordinary 

 mortals feel only secondary interest if they feel any at all 

 but touched mankind itself, its origin, its history, its feelings, 

 its creed, its destiny; and each individual, attacked so to 

 speak directly by the doctrine, was sure to reject it loftily 

 unless irresistible and overwhelming evidence brought con- 

 viction to him, and left him no room for the shadow of 

 a doubt. This was the work left for Darwin to do, and he 

 did it. His contribution to evolutionism was, as we know, 

 not the idea itself; nor was it the idea of descent with 

 modification ; it was the idea of " natural selection " by 

 which he was able to prove plants and animals to have 

 been slowly evolved from simpler forms, "with definite 

 adaptations to the particular circumstances by which they 

 were surrounded." Where an inquirer had seen the law 

 obtaining in flowers only, another inquirer in timber only, 

 a third in mankind only, Darwin showed the law to have 

 held good universally for the whole of organic nature that 

 is, where some had seen the particular he saw the universal ; 

 and he showed this by such a multitude of facts, proofs, 

 instances in so many different species of plants, and so many 

 more of animals, that the conclusion was irresistible. Again, 

 where all the aforesaid philosophers and inquirers had 

 asserted even plausibly, but asserted only, he brought forward 

 innumerable examples of every kind, and silenced dissent 

 by irrefragable proof. Again, where only one line of argu- 

 ment in favour of organic evolution was set forth, Darwin 

 accumulated the argument from palseontological succession, 

 the argument from geographical distribution, the argument 

 from embryological development, the argument from classi- 

 ficatory relationships i.e. 9 the genealogical tree. Where one 

 had seen " descent with modification," he saw descent with 

 modification by "natural selection " which is the key of the 

 mystery. Where Malthus, and even Wallace, had expressed 

 suggestive hints, he constructed a vast inductive system. 

 Finally, where Erasmus Darwin, or Chambers, or Lyell saw 

 the working of a final cause, he saw that of an efficient cause 

 a fundamental distinction, as we shall have again occasion 



