xxxrii.] MENTiVL DEVELOPMENT. 75 



simple inference ; it consists in the power of making siicli 

 inferences as this, that a man must be in the house because 

 his hat is on its peg. 



The next stage of the development of thought consists in 

 the distinctively human power of reasoning. I am not Man's 

 able to see any way of referring all the superiorities of in^eason-'*^ 

 man to any single principle. But so far as the superiority i^S- 

 of man to the highest of the animals is intellectual, I 

 believe it is traceable to the fact, that man has the power, Power of 

 which they have not, of directing his thoughts at will. On thouo-ht 

 this power depends the power of abstraction : and with ?* '*^i'^- 



„ . , Language. 



it the power of using words and other arbitrary signs m Abstrac- 

 speaking and in thinking. *^°^' 



It was a favourite doctrine with Archbishop Whately, VP^hately's 

 that " language is not only the expression of thought, but I'angua^e. 

 the instrument of thought ; " and he maintained that it 

 is impossible to carry on any reasoning process except 

 by the aid of words or other arbitrary signs of essen- 

 tially the same kind, such as the figures of arithmetic 

 or the letters of algebra. And I believe he maintained 

 in connexion with this, and as part of the same theory, 

 that the power of using such arbitrary signs as instru- 

 ments of thought is the distinctively human power, and 

 is at the root of man's intellectual superiority to the 

 lower animals. 



There can be no doubt that this is correct as to the facts. 

 It is possible to make such an inference as that a man 

 must be in the house if his hat is on the peg, without the 

 use of words in the process ; and there are many dogs 

 which are perfectly able to draw such an inference as this. 

 But no one who examines any reasoning process of a much 

 higher kind than this, as it goes on in his own thoughts, 

 will doubt that we think in words ; and that if we were 

 debarred from the use of words in thinking, no elaborate Use of 

 process of thought would be possible to us. But I cannot though" 

 believe the power of making use of words or other arbi- 

 trary signs for the purpose of thinking, to be an inde- 

 pendent and primary power. I think it is the result of 

 something simpler and deeper. I should think so, even if 



