The numerical proportions of different races in the world have, indeed, altered during that period, as one race proved weaker in war or less able to resist disease than another; and races have been mingled by marriage following upon conquest.  But if a baby could now be exchanged at birth with one born of the same breeding-stock even a hundred thousand years ago, one may suppose that neither the ancient nor the modern mother would notice any startling difference.  The child from the Stone Age would perhaps suffer more seriously than our children if he caught measles, or might show somewhat keener instincts in quarrelling and hunting, or as he grew up be rather more conscious than his fellows of the ‘will to live’ and ‘the joy of life.’  Conversely, a transplanted twentieth-century child would resist infectious disease better than the other children in the Stone Age, and might, as he grew up, be found to have a rather exceptionally colourless and adaptable character.  But there apparently the difference would end.  In essentials the type of each human stock may be supposed to have remained unchanged throughout the whole period.  In the politics of the distant future that science of eugenics, which aims at rapidly improving our type by consciously directed selective breeding, may become a dominant factor, but it has had little influence on the politics of the present or the past.

Those new facts in our environment which have produced the enormous political changes which separate us from our ancestors have been partly new habits of thought and feeling, and partly new entities about which we can think and feel.

It is of these new political entities that this chapter will treat.  They must have first reached us through our senses, and in this case almost entirely through the senses of seeing and hearing.  But man, like other animals, lives in an unending stream of sense impressions, of innumerable sights and sounds and feelings, and is only stirred to deed or thought by those which he recognises as significant to him.  How then did the new impressions separate themselves from the rest and become sufficiently significant to produce political results?

The first requisite in anything which is to stimulate us toward impulse or action is that it should be recognisable—­that it should be like itself when we met it before, or like something else which we have met before.  If the world consisted of things which constantly and arbitrarily varied their appearance, if nothing was ever like anything else, or like itself for more than a moment at a time, living beings as at present constituted would not act at all.  They would drift like seaweed among the waves.

The new-born chicken cowers beneath the shadow of the hawk, because one hawk is like another.  Animals wake at sunrise, because one sunrise is like another; and find nuts or grass for food, because each nut and blade of grass is like the rest.

But the recognition of likeness is not in itself a sufficient stimulus to action.  The thing recognised must also be significant, must be felt in some way to matter to us.  The stars reappear nightly in the heavens, but, as far as we can tell, no animals but men are stimulated to action by recognising them.  The moth is not stimulated by recognising a tortoise, nor the cow by a cobweb.