130 THE METHOD OF DARWIN. 



the parallel scratches, they would certainly not 

 have been deeply impressed by them, because 

 they become impressive only when their rela- 

 tion to one another is understood, and this 

 could only be when the glacial theory had 

 been imported from a glacier country. 



The importance of the discovery of the theory 

 of natural selection to the work of Darwin's life 

 will be dwelt upon later. A sigh of relief is 

 embodied in the declaration, " Here, then, I 

 had at last got a theory by which to work." 1 

 Facts cannot be seen without some notion of 

 the relation they will bear to each other when 

 they are found. The stupendous importance 

 of theory for observation is illustrated by the 

 effect of Darwin's theories on biological inves- 

 tigation in all its phases. Huxley put it thus : 

 "The ' Origin' provided us with the working 

 hypothesis we sought." 2 The whole biological 

 world was waiting for it; and when it came it 

 carried the biological sciences into the deduc- 

 tive stage, and opened an era of investigation 

 unprecedented in the rapidity with which dis- 

 covery advanced, and in the accuracy of the 

 results reached. 



There are scattered throughout Darwin's 



1 Life and Letters, Vol. I. p. 68. 



2 Ibid., p. 551. 



