BIOLOGY AND SOCIOLOGY 99 



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 trans- 

 missible by speech and writing, and accordingly tra- 

 dition has come into being, so that modification of 

 behaviour by experience can be operative not only 

 within the individual life, not only from one genera- 

 tion to the next immediately succeeding, as in many 

 mammals, but for an indefinite period. The experi- 

 ence 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; 

 and thus the actual extinction of living matter be 

 increasingly avoided. For instance, we find the sub- 

 stitution of judicial procedure, in which the ideas of 

 two disputants about the matter in dispute are 

 weighed and a selection made in favour of one, for 

 various forms of violence and combat in which one 

 or other of the actual disputants was often elimi- 

 nated. Or again, in struggles between communities, 



8 See Thorndike, op. cit.; Washburn, The Animal Mind. New 

 York; 1913, 



