THE DESCENT OB ORIGIN OF MAN 123 



in tlie sky, from hawks (both, as well as a third cry, intel- 

 ligible to dogs),'' may not some unusually wise ape-like 

 animal have imitated the growl of a beast of prey, and thus 

 void his fellow-monkeys the nature of the expected dan- 

 ger? This would have been a first step in the formation 

 of a language. 



As the voice was used more and more, the vocal organs 

 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 be- 

 tween the continued use of language and the development 

 of the brain has no doubt been far more important. 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 itself, by enabling and encouraging it to carry 

 on long trains of thought. A 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 algebra. It appears, also, that even 

 an ordinary train of thought almost requires, or is greatly 

 facilitated by, some form of language, for the dumb, deaf, 

 and blind girl, Laura Bridgman, was observed to use her ■ 

 fingers while dreaming." Nevertheless, a long succession 

 of vivid and connected ideas may pass through the mind 

 without the aid of any form of language, as we may infer 

 from the movements of dogs during their dreams. "We 

 have, also, seen that animals are able to reason to a cer- 

 tain extent, manifestly without the aid of language. The 

 intimate connection between the brain, as it is now devel- 

 oped in us, and the faculty of speech, is well shown by 



'* Houzeau gives a very curious account of his observations on this suhjeot 

 In his "Pacultds Mentales dea Animaux," torn. ii. p. 348. 



^' See remarks on this head by Dr. Maudsley, "The Physiology and Pathol- 

 ogy of Mind," 2d edit., 1868, p. 199. 



