BIOLOGY AND SOCIOLOGY 97 



is better able to adjust itself to the dangers of life, and 

 once more there is less sacrifice of individuals in the 

 struggle. The same organism persists : but of two 

 possible types of behaviour, the unmodified innate type 

 is eliminated, the type modified by experience survives. 

 If we like to put it in a way which is perhaps not 

 wholly justifiable, there comes into being, besides the 

 struggle for existence between individuals, a struggle 

 for existence between different possible modes of 

 reaction of one and the same organism. 



With the advent of man upon the scene, still new 

 possibilities arise. First of all, he is capable of ideas, 

 which, biologically speaking, are to be regarded as 

 potentialities of behaviour. There is no evidence at 

 present that even the highest animals possess ideas or 

 even images.^ Secondly, these ideas are transmissible 

 by speech and writing, and accordingly tradition has 

 come into being, so that modification of behaviour by 

 experience can be operative not only within the in- 

 dividual life, not only from one generation to the next 

 immediately succeeding, as in many mammals, but 

 for an indefinite period. The experience of Moses, 

 Archimedes, or Charlemagne, of Jesus, Newton, or 

 James Watt is modifying our behaviour to-day. 



The result, both for individuals and communities, 

 is that a selection of ideas instead of a selection of 

 organic units can to an ever greater extent take place ; 



1 See Thomdike, op. cit. ; Washburn, The Animal Mind. 

 New York, 191 3. 



