ANIMAL AND RATIONAL INTELLIGENCE 149 



these preliminary statements, in attempting to trace 

 our path from the shell-fish to man, searching for the 

 appearance of intelligence. 



The initial perplexity attaching to this inquiry is 

 the Hifficulty of finding a reliable definition, of in 

 telligence, such as will be accepted by all. inquirers. 

 This&quot; difficulty is, however, greatly lessened by the 

 course we have followed in drawing the distinction 

 between sensory discrimination and rational dis 

 crimination. There is a clear line of demarcation 

 here, without regard to which it is impossible to 

 advance a single step in our research as to animal 

 intelligence ; and there is this further advantage that 

 the distinction is matter of general agreement. The 

 only modification of this claim to agreement arises 

 from the contention of those who would identify 

 mind with sensibility, or, in case of regarding these 

 as distinct, would make them always co-existent in 

 natural history. Under this hypothesis life and in 

 telligence are either identical or synchronous. Very 

 few among scientific observers are prepared for such 

 a position. 1 Darwin separates himself from this 

 completely, by restricting reference to the higher 

 mammalia, when he seeks to construct a theory of 

 the evolution of man s mental powers. This is not 

 on his part an expedient for restricting the range of 

 comparison. Such restriction might well be desired 

 by any one contemplating the serious entanglements 



1 So stated, biological theory seems to pass into the monistic 

 scheme of Hegel, as in a dissolving view. The Universe is interpreted, 

 not only as the manifestation of creative intelligence, but as the 

 direct action of intelligence, manifesting itself in gradually expand 

 ing rationalised forms, 



