| Comparison with 1866 | 
| 
 | 
| But the chief cause of our natural unwillingness to admit that one species has given birth to other and distinct species, is that we are always slow in admitting any 
great change 
of which we do not see the 
 intermediate 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 
 slow action of the coast-waves.| intermediate 1859 1860 1866 |  | interme- diate 1861 |  | intermediate1869 1872 | 
The mind cannot possibly grasp the full meaning of the term of 
 a hundred| slow action of the coast-waves. 1859 1860 1861 1866 |  | agencies which we see still at work. 1869 1872 | 
million years; it cannot add up and perceive the full effects of many slight variations, accumulated during an almost infinite number of generations.| a hundred 1859 1860 1861 1866 |  | even ten 1869 |  | even a 1872 | 
 | 
|  | 
| 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 ignorance under such expressions as the "plan of creation," "unity of design," &c., and to think that we give an explanation when we only restate 
a fact.  Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject 
 my theory.  A few naturalists, endowed with much flexibility of mind, and who have already begun to doubt 
 on| my 1859 1860 1861 1866 |  | the 1869 1872 | 
the immutability of species, may be influenced by this volume; but I look with confidence to the future, 
to young and rising naturalists, who will be able to view both sides of the question with impartiality.  Whoever is led to believe that species are mutable will do good service by conscientiously expressing his conviction; for 
 only thus| on 1859 1860 1861 1866 |  | on1869 1872 | 
can the load of prejudice by which this subject is overwhelmed be removed.| only thus 1859 1860 1861 1866 |  | thus only 1869 1872 | 
 | 
|  | 
| Several eminent naturalists have of late published | 
 
  
  
| But the chief cause of our natural unwillingness to admit that one species has given birth to other and distinct species, is that we are always slow in admitting 
 any great 
 change| any 1859 1860 1861 1866 1869 |  | any1872 | 
of which we do not see the 
 ..| change 1859 1860 1861 1866 1869 |  | changes 1872 | 
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 see still at work.| ..... 1869 1872 |  | intermediate 1859 1860 1866 |  | interme- diate 1861 | 
The mind cannot possibly grasp the full meaning of the term of 
 even ten| agencies which we see still at work. 1869 1872 |  | slow action of the coast-waves. 1859 1860 1861 1866 | 
million years; it cannot add up and perceive the full effects of many slight variations, accumulated during an almost infinite number of generations.| even ten 1869 |  | a hundred 1859 1860 1861 1866 |  | even a 1872 | 
 | 
|  | 
| 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 ignorance under such expressions as the "plan of creation," "unity of design," &c., and to think that we give an explanation when we only 
 restate a fact.  Any one whose disposition leads him to attach more weight to unexplained difficulties than to the explanation of a certain number of facts will certainly reject 
 the| restate 1859 1860 1861 1866 1869 |  | re-state 1872 | 
theory.  A few naturalists, endowed with much flexibility of mind, and who have already begun to doubt 
 ..| the 1869 1872 |  | my 1859 1860 1861 1866 | 
the immutability of species, may be influenced by this volume; but I look with confidence to the 
 future,| ..... 1869 1872 |  | on 1859 1860 1861 1866 | 
to young and rising naturalists, who will be able to view both sides of the question with impartiality.  Whoever is led to believe that species are mutable will do good service by conscientiously expressing his conviction; for 
 thus only| future, 1859 1860 1861 1866 1869 |  | future,— 1872 | 
can the load of prejudice by which this subject is overwhelmed be removed.| thus only 1869 1872 |  | only thus 1859 1860 1861 1866 | 
 | 
|  | 
| Several eminent naturalists have of late published |