xii INTRODUCTION 



found its expression in the " Doctrine of 

 Natural Selection." Each of these two great 

 advances of thought is thus the philosophic 

 epic of a great nation at its epoch; and 

 Lamarck and Darwin are their representative 

 prophets respectively. 



In the generation after Darwin research 

 was necessarily actively specialized in biology; 

 and the social perspective, with its conscious 

 application to evolutionary research, has been 

 little employed by naturalists since Darwin 

 and Wallace, despite its extraordinary fruit- 

 fulness in their hands. Now, however, it 

 begins to return, witness the Eugenic move- 

 ment : and in these pages we shall not hesitate 

 to avail ourselves of it. 



We may even utilize it for teaching pur- 

 poses, beginning with the doctrine of natural 

 selection. As Paley's famous "watch argu- 

 ment " appeared at the outset of the 

 mechanical age, so again at its culmination 

 we may avail ourselves of the conspicuous 

 progress of invention to explain and illustrate 

 Darwin's great doctrine. In fact, we may 

 socratically elicit it from the freshman who 

 supposes himself quite unacquainted with 

 biology or its theories. For he knows the 

 points of a bicycle, and something of the 

 story of its development from his father's 



