The Origin of Species 



mutable productions was almost unavoidable as 

 long as the history of the world was thought to 

 be of short duration; and now that we have 

 acquired some idea of the lapse of time, we are 

 too apt to assume, without proof, that the geo- 

 logical record is so perfect that it would have 

 afforded us plain evidence of the mutation of 

 species, if they had undergone mutation. 



But the chief cause of our natural unwilling- 

 ness to admit that one species has given birth to 

 other and distinct species, is that we are always 

 slow in admitting great changes of which we do 

 not see the steps. The difficulty is the same as 

 that felt by so many geologists, when Lyell first 

 insisted that long lines of inland cliffs had been 

 formed, and great valleys excavated, by the 

 agencies which we still see at work. The mind 

 cannot possibly grasp the full meaning of the 

 term^of even a million years; it cannot add up 

 and perceive the full effects of many slight varia- 

 tions, accumulated during an almost infinite num- 

 ber of generations. 



Although I am fully convinced of the truth of 

 the views given in this volume under the form of 

 an abstract, I by no means expect to convince 

 experienced naturalists whose minds are stocked 

 with a multitude of facts all viewed, during a long 

 course of years, from a point of view directly 

 opposite to mine. It is so easy to hide our ignor- 

 ance under such expressions as the "plan of 

 creation," "unity of design," etc., and to think 

 that we give an explanation when we only re- 

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