MAN'S BRAIN 501 



because of the constitution of his brain, to make infinitely more 

 complex structures. 



517. Fire. What the use of fire has meant to man is hard 

 for most of us to realize, because we have always had the bene- 

 fits of fire, and grow up accepting it as a matter of course. It 

 made possible his wandering from the tropics ; it made possible 

 his descent from the trees to dwell in caves or even in the 

 open, for with fire he could keep the beasts away ; it made 

 available to him food that he could otherwise not use ; and it 

 was probably helpful in early times in many other ways. 



It is not to be wondered that people of all races and in all times 

 have not only seen in fire a great benefactor, but have been impelled 

 to worship the mystery of it as well. Even in our own times the 

 symbolism associated with fire still persists in festivals and religious 

 ceremonials. 



518. Speech. Many animals are capable of making several 

 distinct sounds that actually serve as means of warning or 

 other communication between members of the species. The 

 hen, for example, can utter some twenty distinct sounds, and 

 each one has a different meaning. Other animals have been 

 observed to communicate with each other by means of calls 

 or cries. But in human speech there is more than a set of 

 significant ejaculations. Human language comes to be built up 

 into words, each of which consists of definite successions of 

 sound (which we represent by means of vowels and conso- 

 nants), and these words are combined into sentences capable 

 of expressing all kinds of ideas. Of course one may say that 

 our language is more complex because our thoughts are more 

 complex, and that is true enough. But human speech differs 

 from the crowing and growling and snarling of other animals 

 in what may be called its structural possibilities as well as in 

 its actual complexity, it is capable of constant readjustment 

 to the needs of the thinking animal in a way that the expres- 

 sions of other animals are not, For example, if you have a 



