Chap. II.] MENTAL POWERS. 55 



rise to words expressive of various complex emotions. As 

 bearing on the subject of imitation, the strong tendency 

 in our nearest allies, the monkeys, in microcephalous 

 idiots, 35 and in the barbarous races of mankind, to imi- 

 tate whatever they hear deserves notice. As monkeys 

 certainly understand much that is said to them by man, 

 and as in a state of nature they utter signal-cries of dan- 

 ger to their fellows, 36 it does not appear altogether incred- 

 ible, that some unusually wise ape-like animal should have 

 thought of imitating the growl of a beast of prey, so as 

 to indicate to his fellow-monkeys the nature of the ex- 

 pected danger. And this would have been a first step in 

 the formation of a language. 



As the voice was used more and more, the vocal or- 

 gans would have been strengthened and perfected through 

 the principle of the inherited effects of use; and this 

 would have reacted on the power of speech. But the 

 relation between the continued use of language and the 

 development of the brain has no doubt been far more im- 

 portant. The mental powers in some early progenitor of 

 man must have been more highly developed than in any 

 existing ape, before even the most imperfect form of 

 speech could have come into use ; but we may confidently 

 believe that the continued use and advancement of this 

 power would have reacted on the mind by enabling and 

 encouraging it to carry on long trains of thought. A 

 long and complex train of thought can no more be carried 

 on without the aid of words, whether spoken or silent, 

 than a long calculation without the use of figures or alge- 

 bra. It appears, also, that even ordinary trains of thought 



35 Vogt, * Memoire sur les Microcephales,' 1867, p. 169. With re- 

 spect to savages, I have given some facts in my ' Journal of Researches,' 

 etc., 1845, p. 206. 



36 See clear evidence on this head in the two works so often quoted, 

 by Brehm amd Rengger. 



