rtaken in
order to meet some great necessity, and must have become possible by
reason of some great force which man alone possessed. The necessity
was economic; the force was social development. If the movement has
not been geographically ever forward, it has been ethnographically
constant.[298] Movement always; sometimes the pressure has come from
one direction, sometimes from another; sometimes it has caused
compression and at other times expansion; sometimes it has sent
humanity to inhabit regions that required generations of victims
before it could hold its own. At all times the essential condition of
life has been that of constant movement in face of antagonistic
forces.[299] In whatever form the movement has come about, movement of
a very definite character has taken place over an immense period of
time, and sufficient to cover practically the whole earth with
descendants from the original human stock. This conclusion is
enormously strengthened by the accumulating evidence for the
world-wide area covered by the remains of man's earliest weapon, the
worked stone implement. It is everywhere. It is practically
co-extensive with man's wanderings, and the greatness of the territory
it covers marks it off as another of the universal relics of man's
primitive life. Of no other weapon or instrument or associated object
can this be said. The bow and arrow are unknown to the Australians and
other peoples; pottery is unknown to the Bushmen and other peoples;
the use of fire in cookery is not found among the South Sea Islanders,
and is not claimed for other peoples.[300] We can get behind the
development of these and other arts and come upon the ruder people who
had not arrived at the stage they represent. But we cannot get behind
the worked flint. It must have been the chief material cause of man's
success in the migratory movement, and with the social development
accompanying it must have made migration not only possible, but the
only true method of meeting the earliest economic difficulties. It
also provides us with the elements of a chronological basis. Behind
palaeolithic times there is an immensity of time when man struggled
with his economic difficulties and spread out slowly and painfully.
During palaeolithic times the movement was more rapid and more general.
Obstacles were overcome by palaeolithic man becoming superior to his
enemies by the use of weapons, and use of weapons caused, or at all
events aided, the devel