136 CREATIVE EVOLUTION 



second, but cannot continue in it without being drawn 

 aside from its direction, as would happen to a man 

 leaping, if, in order to clear the obstacle, he had to 

 turn his eyes from it and look at himself all the while. 

 Living forms are, by their very definition, forms 

 that are able to live. In whatever way the adaptation of 

 the organism to its circumstances is explained, it has 

 necessarily been sufficient, since the species has subsisted. 

 In this sense, each of the successive species that paleon 

 tology and zoology describes was a success carried off by 

 life. But we get a very different impression when we 

 refer each species to the movement that has left it behind 

 on its way, instead of to the conditions into which it has 

 been set. Often this movement has turned aside ; very 

 often, too, it has stopped short ; what was to have been 

 a thoroughfare has become a terminus. From this new 



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point of view, failure seems the rule, success exceptional 

 and always imperfect. We shall see that, of the four 

 main directions along which animal life bent its course, 

 two have led to blind alleys, and, in the other two, the 

 effort has generally been out of proportion to the result. 

 Documents are lacking to reconstruct this history in 

 detail, but we can make out its main lines. We have 

 already said that animals and vegetables must have 

 separated soon from their common stock, the vegetable 

 falling asleep in immobility, the animal, on the con 

 trary, becoming more and more awake and marching on 

 to the conquest of a nervous system. Probably the effort 

 of the animal kingdom resulted in creating organisms 

 still very simple, but endowed with a certain freedom 

 of action, and, above all, with a shape so undecided 

 that it could lend itself to any future determination. 

 These animals may have resembled some of our worms, 

 but with this difference, however, that the worms living 



