344 HABIT AND INTELLIGENCE. [cHAP. 



otter sheep) are crossed with other breeds, the offspring, 

 with rare exceptions, perfectly resemble either parent." ^ 

 For these reasons, I think there is no improbability in 

 sudden, as well as slow, variations occurring among 

 organisms in the wild state ; though, as wild organisms 

 are much less variable than domestic ones, they must 

 occur much more rarely.^ It may be true that we have no 

 evidence of the origin of wild species in this way. But 

 this is not a case in which negative evidence proves any- 

 Sudden thing. We have never witnessed the origin of a wild 

 "^vm'^ °^^ species by any process whatever ; and if a species were to 

 would not come suddenly into being in the wild state, as the Ancon 

 covered, sheep did under domestication, how could we ascertain the 

 fact 1 If the first of a newly-begotten species were found, 

 the fact of its discovery would tell notliing about its 

 origin. ISTaturalists would register it as a very rare species, 

 having been only once met with, but they would have no 

 means of knowing whether it were the first or the last of 

 its race. 

 Geological I consequently think that sudden variation is not only 

 shoiVfor possible, but probable. And I further doubt whether the 

 the theory development theory is tenable unless we admit it. I am 

 variation, inclined to think that geological time is too short for the 

 evolution of the higher forms of life out of the lower 

 by that accumulation of imperceptibly slow variations, to 

 which alone Darwin ascribes the whole process. 



This will surprise many readers. It is almost as start- 

 ling now to be told that geological time is less than infinite, 

 as it would have been a hundred years ago to be told that 

 historical time was but a small fraction of the age of the ' 

 earth. Nevertheless, the reasoning which has been briefly 

 stated in the chapter on "the Motive Powers of the 

 Universe," proves that the order of things on the earth 

 earth ^^ must have had a beginning ; and Sir William Thomson 

 according j^g^g roughly estimated the past duration of the solar 



to Sir W. o J j^ 



Thomson, system in its present state at about five hundred millions 



1 Darwin's Variation under Domestication, vol. L p. 100. 



2 "Sports" are extremely rare under nature, but far from rare under 

 domestication. (Darwin's Origin of Species, p. 10.) 



