132 THE DOCTRINE OF DESCENT. 



ponents of the great inquirer endeavour to suppress his 

 merits and authority by maintaining that he is properly 

 a mere dilettante, dealing with general abstractions,^* a 

 stranger to the keen observation which takes full ac- 

 count of facts. How Darwin arrived at the idea which 

 has made an epoch in science, he has himself made 

 known in the introduction to his first work on the doc- 

 trine of Descent, namely, the " Origin of Species; " ^^ and 

 in more detail in a letter to Haeckel, published by the 

 latter in his " History of Creation " (Natiirlichen Schop- 

 fungsgeschichte). 



" Having reflected much on the foregoing facts, it 

 seemed to me probable that allied species were descended 

 from a common ancestor. But during several years I 

 could not conceive how each form could have been modi- 

 fied so as to become admirably adapted to its place in 

 nature. I began, therefore, to study domesticated ani- 

 mals and cultivated plants, and after a time perceived 

 that man's power of selecting and breeding from cer- 

 tain individuals was the most powerful of all means in 

 the production of new races. Having attended to the 

 habits of animals and their relations to the surround- 

 ing conditions, I was able to realize the severe strug- 

 gle for existence to which all organisms are subjected; 

 and my geological observations had allowed me to ap- 

 preciate to a certain extent the duration of past geolog- 

 ical periods. With my mind thus prepared I fortunatel\' 

 happened to read Malthus's ' Essay on Population ; ' 

 and the idea of natural selection through the strug- 

 gle for existence at once occurred to me. Of all 

 the subordinate points in the theory, the last which I 

 understood was the cause of the tendency in the de- 



