ngled 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