THE ARGUMENTS FROM CLASSIFICATION. 443 



Greek and certain extinct and spoken languages of the East, 

 are shown to have traits in common whicli unite them into 

 one great class known as Aryan languages; radically dis- 

 tinguished from the classes of languages spoken by the other 

 main divisions of the human race. 



§ 123. Now this kind of subordination of groups which we 

 see arises in the course of continuous descent, multiplication, 

 and divergence, is just the kind of subordination of groups 

 which plants and animals exhibit: it is just the kind of 

 subordination which has thrust itself on the attention of 

 naturalists in spite of pre-conceptions. 



The original idea was that of arrangement in linear order. 

 We saw that even after a considerable acquaintance with the 

 structures of organisms had been acquired, naturalists con- 

 tinued their efforts to reconcile the facts with the notion of a 

 uni-serial succession. The accumulation of evidence necessi- 

 tated the breaking up of the imagined chain into groups and 

 sub-groups. Gradually there arose the conviction that these 

 groups do not admit of being placed in a line. And the con- 

 ception finally arrived at, is that of certain great sub-king- 

 doms, very widely divergent, each made up of classes much 

 less divergent, severally containing orders still less divergent; 

 and so on with genera and species. 



Hence this " grand fact in natural history of the subordi- 

 nation of group under group, which from its familiarity does 

 not always sufficiently strike us," is perfectly in harmony 

 with the hypothesis of evolution. The extreme significance 

 of this kind of relation among organic forms is dwelt on by 

 Mr. Darwin, who shows how an ordinary genealogical tree 

 represents, on a small scale, a system of grouping analogous 

 to that which exists among organisms in general, and which is 

 explained on the supposition of a genealogical tree by which 

 all organisms are affiliated. If, wherever we can trace direct 

 descent, multiplication, and divergence, this formation of 

 groups within groups takes place; there results a strong pre- 



