EVOLUTION THEORIES 231 



and chemists, nor of the puzzled mysticism 

 of vitalist philosophers as yet befogged by 

 their urban environments or bewildered by 

 reaction from it. It will be in terms of 

 biology proper, and its processes of nutrition 

 and reproduction, of metabolism and growth. 

 Each science is but an aspect of the whole, a 

 pictured facet of Nature's unity, but it has 

 its own categories, its own values. No one 

 of the main sciences, be they the objective 

 physical, biological, social; or the subjective 

 ethic, psychologic, aesthetic is intelligibly 

 reducible into the concepts of any other, 

 those of mechanics, physics, chemistry, de- 

 spite their long exaggerated pretensions, as 

 little as any (though their parallelisms may 

 and should be sought; that is a practicable 

 and legitimate inquiry). It tells us nothing 

 of the aesthetic value of scarlet blossom, of 

 golden sunset, of summer green, that these 

 have such and such relations of wave-length, 

 interesting in the physical laboratory though 

 that be. By all means let us correlate brain 

 growth with mind; but the life of intelli- 

 gence, idealism, imagination, would have 

 none the less its psychological independence 

 were the chemical formulae of every brain 

 metabolism published to-morrow. 



So then for biology. Its theory of life, of 



