ANIMAL AND RATIONAL INTELLIGENCE 217 



both conclusively made out, it is not shown that the 

 law is capable of effecting such advance, in structure, 

 or in life-action, as intelligence implies. Granting 

 some degree of variation in instincts under a state 

 of Nature, and the inheritance of such variations, as 

 indispensable for the action of natural selection, 1 

 it does not seem that appearance of Intelligence 

 among the higher mammals is being accounted for. 

 On the evidence of differentiation, it is not possible 

 to argue that variations are on the way to intelli 

 gence, or in any sense preparatory for its appearance. 

 Still less can such a claim be made on the ground of 

 slight modifications of structure, occurring under 

 the law of natural selection. It does not seem that 

 any variation of structure, or any advance in function, 

 or any manifestation of instinct, has been discovered, 

 in the history of lower orders of life, which will 

 account for the appearance of animal intelligence. 

 After structural variations have been explained, ani 

 mal intelligence stands unexplained. It is here, as 

 it seems in testing the evidence, that a limit in the 

 line of evolution appears. A break comes into view at 

 a stage lower than the appearance of rational life. 



Variation of Intelligence is as certain as is variation 

 in Instinct, but the one cannot be accounted for 

 under natural selection, as the other can be. Food 

 has affinity with structure ; it has only a remote 

 relation to action of intelligence. Even the success 

 of an evolution scheme, gives vividness to this con 

 trast. Intelligence is a phase of life exempt from laws 

 of nutriment. Mind, even closely related as it is with 

 body, is superior to laws of nutriment. Until we have 



1 Origin oj Species, p. 194. 



