| Comparison with 1872 | 
| 
 | 
| now that we have acquired some idea of the lapse of time, we are too apt to assume, without proof, that the geological 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 unwillingness to admit that one species has given birth to other and distinct species, is that we are always slow in admitting 
 .. great 
 changes| ..... 1872 |  | any 1859 1860 1861 1866 1869 | 
of which we do not see the 
 ..| changes 1872 |  | change 1859 1860 1861 1866 1869 | 
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 a| 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 a 1872 |  | a hundred 1859 1860 1861 1866 |  | even ten 1869 | 
 | 
|  | 
| 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 
 re-state 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| re-state 1872 |  | restate 1859 1860 1861 1866 1869 | 
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| future,— 1872 |  | future, 1859 1860 1861 1866 1869 | 
 | 
 
  
  
| now that we have acquired some idea of the lapse of time, we are too apt to assume, without proof, that the geological 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 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 
 intermediate| 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 
 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| 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 
 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,| on 1859 1860 1861 1866 |  | on1869 1872 | 
to young and rising naturalists, who will be able to| future, 1859 1860 1861 1866 1869 |  | future,— 1872 | 
 |