An Introduction to a Biology 



If I believed the first alternative I should think 

 that his certainty was due to the perfect fit between 

 theory and phenomenon ; if I believed the second 

 I should think that certainty was due to absence 

 of fit between theory and phenomenon. Certainty 

 can be bred in the mind by these two extremes ; 

 not by an intermediate stage. Are there any theories 

 concerning vital phenomena about which certainty 

 can be due to perfect fit ? Can there be any vital 

 phenomenon that we know so intimately in every 

 undulation of its form, every nuance of its colour, 

 or every phase of its movements that there can be 

 a theory which fits all this exactly ? Possibly in 

 the case of some exceedingly simple phenomena (if 

 such exist), certainty is due to perfect fit. But does 

 it seem likely that, for instance, the certainty in the 

 mind of so many that Natural Selection is the ex- 

 planation of evolution, that tremendous phenomenon 

 of the growth of life, the features of which we can 

 but dimly discern, does it seem likely that this 

 certainty can be due to perfect fit ? 



An old artist and a young artist both arrived in 

 Venice not long ago, on the same day. At the end 

 of a month the old artist had painted nothing ; it 

 was too beautiful ; he knew he was not equal to 

 painting a picture which could express to him the 

 manifold magic of the place ; he knew that nothing 

 that he could produce would fit reality. The young 

 artist, however, made many sketches, with each of 

 which he was well pleased. He had no difficulty 

 in expressing what he saw, because he saw so much 

 less than the old man did. Nor would he know that 

 he saw less because Venice to him would be the 



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