430 THE ORIGIN OF SPECIES 



occur. Nature may be said to have taken pains to reveal her 

 scheme of modification, by means of rudimentary organs, of em- 

 bryological and homologous structures, but we are too blind to 

 understand her meaning. 



I have now recapitulated the facts and considerations which 

 have thoroughly convinced me that species have been modified, 

 during a long course of descent. This has been effected chiefly 

 through the natural selection of numerous successive, slight, favor- 

 able variations ; aided in an important manner by the inherited ef- 

 fects of the use and disuse of parts ; and in an unimportant manner, 

 that is, in relation to adaptive structures, whether past or present, 

 by the direct action of external conditions, and by variations 

 which seem to us in our ignorance to arise spontaneously. It ap- 

 pears that I formerly underrated the frequency and value of these 

 latter forms of variation, as leading to permanent modifications 

 of structure independently of natural selection. But as my con- 

 clusions have lately been much misrepresented, and it has been 

 stated that I attribute the rnodification of species exclusively to 

 natural selection, rinay^i~pefmltted to remark that in the first 

 edition of this work, and subsequently, I placed in a most con- 

 spicuous position — namely, at the close of the Introduction — the 

 following words: "I am convinced that natural selection has been 

 the main but not the exclusive means of modification." This has 

 been of no avail. Great is the power of steady misrepresentation; 

 but the history of science shows that fortunately this power does 

 not long endure. 



It can hardly be supposed that a false theory would explain, 

 in so satisfactory a manner as does the theory of natural selec- 

 tion, the several large classes of facts above specified. It has re- 

 cently been objected that this is an unsafe method of arguing; 

 but it is a method used in judging of the common events of life, 

 and has often been used by the greatest natural philosophers. The 

 undulatory theory of light has thus been arrived at ; and the belief 

 in the revolution of the earth on its own axis was until lately 

 supported by hardly any direct evidence. It is no valid objection 

 that science as yet throws no light on the far higher problem of 

 the essence or origin of life. Who can explain what is the essence 

 of the attraction of gravity? No one now objects to following out 

 the results consequent on this unknown element of attraction; 

 notwithstanding that Leibnitz formerly accused Newton of in- 

 troducing "occult qualities and miracles into philosophy." 



I see no good reasons why the views given in this volume 

 should shock the religious feelings of any one. It is satisfactory, 



