112 THE EVOLUTION OF MAN. 



any longer tell the fable of " the moral ordering of the 

 world." It exists neither in nature nor in human life, 

 neither in natural history, nor in the history of civilization. 

 The terrible and ceaseless " Struggle for Existence " gives 

 the real impulse to the blind course of the world. A 

 "moral ordering," and "a purposive plan" of the world 

 can only be visible, if the prevalence of an immoral rule 

 of the strongest and undesigned organization is entirely 

 ignored. 



The Natural System of Organisms, which classifies all 

 the various forms in larger and smaller groups, according to 

 the degree of similarity or dissimilarity of these forms, is 

 the widest inductive basis of the Theory of Descent. 

 These groups or categories of the system, the varieties 

 species, genera, families, orders, classes, and so on, always 

 show such relative co-ordination and subordination that 

 they can be explained only genealogically, and the whole 

 system can but be represented figuratively under the form of 

 a tree with many branches. This tree is the genealogical 

 tree of the groups related in form, and their relation in 

 form really is their relation in blood. As no other explana- 

 tion can be given of the fact that the system naturally 

 assumes a tree-like form, we may regard this as an imme- 

 diate and powerful proof of the truth of the Doctrine of 

 Descent. 



Among the most important of the phenomena, testify- 

 ing to the inductive law of the Theory of Descent, is the 

 geographical distribution of animal and vegetable species 

 over the surface of the earth, and their topographical distri- 

 bution on the heights of mountains and in the depths of 

 oceans. Alexander Humboldt gave a fresh impulse to the 



