INTRODUCTION xi 



doctrines. Of this social ferment of evolu- 

 tionary thought there have been as yet two 

 main phases; and first the French eighteenth 

 century "Progress of Humanity," that char- 

 acteristic doctrine of the Encyclopedists and 

 Physiocrats, of Rousseau, and of the Revo- 

 lution at its best, and this expressed for 

 history by Condorcet, for living nature by 

 Lamarck. The second phase is that of the 

 Industrial Revolution in Britain, from Watt 

 and Arkwright to Stephenson and Wheat- 

 stone; and thence to a nineteenth-century 

 manufacturing and commercial world-pre- 

 dominance, proportionately culminating from 

 1851 to 1860 or thereby; with its character- 

 istic "self-made men,' its colonial expan- 

 sion and growing empire. 



It was the former period, with its theories 

 of society and of morals, which gave birth 

 to the "Doctrine of Evolution"; while the 

 latter period, with its competitive industry, 

 its resultant "population question," etc., has 

 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; 



