MENTAL POWERS. 99 



cry, intelligible to dogs*), may not some unusually wise 

 ape-like animal have imitated the growl of a beast of prey, 

 and thus told his fellow-monkeys the nature of the expected 

 danger? This would have been a first step in the forma- 

 tion 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, f 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. AVe have, also, seen that animals are able to 

 reason to a certain extent, manifestly without the aid of 

 language. The intimate connection between the brain, as 

 it is now developed in us, and the faculty of speech, is 

 well shown by those curious cases of brain-disease in which 

 speech is specially affected, as when the power to remem- 

 ber substantives is lost, while other words can be correctly 

 used, or where substantives of a certain class, or all 

 except the initial letters of substantives and proper 



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

 subject in his " Facultes Mentales des Animaux," torn, ii, p. 348. 



f See remarks on this head by Dr. Maudsley, " The Physiology 

 and Pathology of Mind," 2d edit.. 1868, p. 198. 



