4 Darwin's Predecessors 



of what occurs in the case of domestic animals and cultivated plants, 

 and by his elaboration of the theory of Natural Selection, which 

 Alfred Russel Wallace independently stated at the same time, and of 

 which there had been a few previous suggestions of a more or less 

 vague description. It was here that Darwin's originality was greatest, 

 for he revealed to naturalists the many different forms — often very 

 subtle — which natural selection takes, and with the insight of a 

 disciplined scientific imagination he realised what a mighty engine of 

 progress it has been and is. 



(IV) As an epoch-marking contribution, not only to ^Etiology 

 but to Natural History in the widest sense, we rank the picture 

 which Darwin gave to the world of the web of life, that is to say, of 

 the inter-relations and linkages in Nature. For the Biology of the 

 individual — if that be not a contradiction in terms — no idea is more 

 fundamental than that of the correlation of organs, but Darwin's 

 most characteristic contribution was not less fundamental, — it was 

 the idea of the correlation of organisms. This, again, was not novel ; 

 we find it in the works of naturalists like Christian Conrad Sprengel, 

 Gilbert White, and Alexander von Humboldt, but the realisation of 

 its full import was distinctively Darwinian. 



As Regards the General Idea of Organic Evolution. 



While it is true, as Prof. H. F. Osborn puts it, that " ' Before and 

 after Darwin ' will always be the ante et post urbem conditam of 

 biological history," it is also true that the general idea of organic 

 evolution is very ancient. In his admirable sketch From the Greeks 

 to Darwin 1 , Prof. Osborn has shown that several of the ancient 

 philosophers looked upon Nature as a gradual development and as 

 still in process of change. In the suggestions of Empedocles, to take 

 v- the best instance, there were " four sparks of truth, — first, that the 

 development of life was a gradual process ; second, that plants were 

 evolved before animals; third, that imperfect forms were gradually 

 replaced (not succeeded) by perfect forms ; fourth, that the natural 

 cause of the production of perfect forms was the extinction of the 

 imperfect 2 ." But the fundamental idea of one stage giving origin to 

 another was absent. As the blue iEgean teemed with treasures of 

 beauty and threw many upon its shores, so did Nature produce like a 

 fertile artist what had to be rejected as well as what was able to 

 survive, but the idea of one species emerging out of another was not 

 yet conceived. 



1 Columbia University Biological Series, Vol. i. New York and London, 1894. We 

 must acknowledge our great indebtedness to this fine piece of work. 



2 op. cit. p. 41. 





