us," a material made of the
fibres of a plant. Short inscriptions over the entrances of temples and
palaces, or cut with the chisel on monuments erected in memory of great
events or above the graves of famous men, and long inscriptions covering
whole walls or even the face of high rocks smoothed for the purpose,
were like so many stone books, pages of which are continually discovered
and read by our scholars.

But we come at last to times so remote that there is not a trace of the
roughest writing, not a fragment of the crudest monument, to tell us the
story of the men who, then as now, must have thought and labored and
invented, only so much more slowly, under difficulties which we can
hardly picture to ourselves. "What, then," is the natural question,
"what can we know of such times, and of earlier ones still? How do we
know things happened in the manner described a few pages back?" We know
it, in the first place, _by analogy_, _i.e._, because the same things
have happened over and over again in the same manner in times which we
know all about, _and are happening now, under our eyes_--for what is the
constant tide of immigration which keeps coming in from the East but,
under modern conditions, the same swarming off from overcrowded native
hives of seekers after more land and new fortunes? In the second place,
the oldest races of the world left abundant traces by which we can
determine not only the places of their settlements, but their mode of
life and the degree of culture they successively reached.

There has certainly been a time when men did not know enough to build
dwellings for themselves--or, not to be unfair, had not the necessary
tools--but lived in the forests which then very nearly covered the
globe, using such natural shelter as they found ready for them, almost
like the savage animals which it was their main business to fight and
kill in self-defence and also for food and clothing. Caverns in steep
mountain-sides must have been their most luxurious, because safest and
best-protected, retreats. Many dozens of such caverns are known in all
parts of the world, and the tale they tell is not difficult to read.
Several have become very famous, from the wealth of finds with which
they rewarded the searchers. Some appear to have been used as
burying-places, for the ground in them is covered to a great depth with
broken-up human skulls and skeletons, while outside, on the rocky ledges
or platforms before the mout