424 THE ASCENT OF MAN 



in question does not manifest itself at all. If we 

 carry the animal back to protoplasm, it may 

 readily seem possible to explain it as a chemical 

 compound. And, in like manner, by the same 

 minimizing process, we may seem to succeed in 

 reducing consciousness and self-consciousness in its 

 simplest form to sensation, and sensation in its 

 simplest form to something not essentially different 

 from the nutritive life of plants. The fallacy of 

 the sorites may thus be used to conceal all quali- 

 tative changes under the guise of quantitative 

 addition or diminution, and to bridge over all 

 difference by the idea of gradual transition. For, 

 as the old school of etymologists showed, if we 

 are at liberty to interpose as many connecting 

 links as we please, it becomes easy to imagine 

 that things the most heterogeneous should spring 

 out of each other. While, however, the hypothesis 

 of gradual change — change proceeding by infinitesi- 

 mal stages which melt into each other so that 

 the eye cannot detect where one begins and the 

 other ends — makes such a transition easier for 

 imagination^ it does nothing to diminish the diffi- 

 culty or the wonder of it for thoughtr^ 



The value of philosophical criticism to science 

 has seldom appeared to more advantage than in 

 ' Edward Caird, The Evolution of Religion, Vol. I., pp. 49-50. 



