294 CONCLUSION. [Chap. XV. 



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 

 ot attraction ; notwithstanding that Leibnitz formerly 

 accused ]S^e^vton of introducing "occult qualities and 

 miracles into philosophy.^ 



[I see no good reason why the views given in this volume 

 should shock the religious feelings of any one. It is 

 satisfactory, as showing how transient such impressions 

 are, to remember that the greatest discovery ever made 

 by man, namely, the law of the attraction of gravity, 

 was also attacked by Leibnitz, " as subversive of natural, 

 and inferentially of revealed, religion." A celebrated 

 author and divine has written to me that " he has gradu- 

 " ally learnt to see that it is just as noble a conception 

 " of the Deity to believe that He created a few original 

 " forms capable of self-development into other and need- 

 " ful forms, as to believe that He required a fresh act of 

 " creation to supply the voids caused by the action of 

 " His laws.^ 



^''hy, it may be asked, until recently did nearly aU 

 the most eminent living naturalists and geologists dis- 

 believe in the mutability of species. It cannot be 

 asserted that organic beings in a state of nature are 

 subject to no variation ; it cannot be proved that the 

 amount of variation in the course of long ages is a limited 

 quantit^j no clear distinction has been, or can be, drawn 

 between species and well-marked varieties, ^t cannot 

 be maintained that species when intercrossed are invari- 



