THE THEORY OF ORGANIC EVOLUTION 179 



identical with those which had been reached by Darwin 

 after years of study. But so great was Darwin's generosity 

 and modesty that his first impulse was to publish Wallace's 

 views without any mention of his own work. Fortunately, 

 Lyell, and Hooker, the botanist, both of whom knew the 

 history of Darwin's work, persuaded him to announce the 

 results of his own studies in a similar formulation. This he 

 consented to do and was also persuaded to prepare the more 

 extended statement which appeared a year later as the 

 " Origin of Species." 22 



The publication of this work marked the beginning of a 

 new epoch, both in biological science and human thought. 

 The origin of the human species was only suggested, its 

 discussion being reserved for a later volume, the " Descent of 

 Man" (1871). The dramatic features attendant upon the 

 publication and promulgation of Darwin's views are well 

 known. In 1900, the " Origin" was rated as one of the half 

 dozen books of the century in the number of copies printed. 

 What is less well understood, even at the present day, is 

 the exact nature of Darwin's scientific accomplishment and 

 its significance in the history of human thought. 



Darwin's work accomplished two things in biological 

 science: in the first place, it established organic evolution 

 as the only reasonable explanation of the past history of 

 living things; and secondly, it offered, in natural selection, 

 what then appeared an adequate explanation for the origin 

 of species and hence for the causes of evolution. Darwin's 

 essential argument in the " Origin of Species" was that one 

 species could give rise to another "by means of natural 

 selection or the preservation of favored races in the struggle 



22 The cordial relations which existed between Darwin and Wallace and the 

 generosity exhibited by both is one of the cherished traditions of biological 

 science. The case might have been very different, since there was abundant 

 opportunity for professional jealousy. Because of their mutual generosity, 

 history accords to Darwin and Wallace a joint position as discoverers of 

 natural selection, although it recognizes the priority which should be accorded 

 to Darwin because of his earlier and more extended studies. 



