Its psychological constitution is reducible to two elements: slightly concrete images, schemas approaching general ideas; for their association, relations predominantly rational, more the products of the logic of the intellect than of the logic of the feelings.
But scientists are far from agreed on the value of explanations and schemas of this sort. Chemists have pointed out that even in the organic not to go so far as the organized science has reconstructed hitherto nothing but waste products of vital activity; the peculiarly active plastic substances obstinately defy synthesis.