240 The Outline of Science 



or Mankind, or Humanity. Experimenting with concepts or 

 general ideas is what we call Reason. 



Here, of course, we get into deep waters, and perhaps it is 

 wisest not to attempt too much. So we shall content ourselves 

 here with pointing out that Man's advance in intelligence and 

 from intelligence to reason is closely wrapped up with his power 

 of speech. What animals began a small vocabulary he has 

 carried to high perfection. But what is distinctive is not the 

 vocabulary so much as the habit of making sentences, of express- 

 ing judgments in a way which admitted of communication be- 

 tween mind and mind. The multiplication of words meant much, 

 the use of words as symbols of general ideas meant even more, for 

 it meant the possibility of playing the internal game of thinking; 

 but perhaps the most important advance of all was the means of 

 comparing notes with neighbours, of corroborating individual 

 experience by social intercourse. With words, also, it became 

 easier to enregister outside himself the gains of the past. It is 

 not without significance that the Greek Logos, which may be 

 translated "the word," may also be translated Mind. 



9 

 Looking Backwards 



When we take a survey of animal behaviour we see a long 

 inclined plane. The outer world provokes simple creatures to 

 answer back; simple creatures act experimentally on their sur- 

 roundings. From the beginning this twofold process has been 

 going on, receiving stimuli from the environment and acting 

 upon the environment, and according to the efficiency of the 

 reactions and actions living creatures have been sifted for mil- 

 lions of years. One main line of advance has been opening new 

 gateways of knowledge the senses, which are far more than 

 five in number. The other main line of advance has been in most 

 general terms, experimenting or testing, probing and proving, 

 trying one key after another till a door is unlocked. There is 



