world, all the way back to the beginning.

The task is quite easy, so long as we have books to help us, histories
to tell us year by year all that went on in every part of the Great
Round World, as our newspapers tell us day by day what is going on in it
now. But books do not take us very far back. It is only four hundred
years since printing was invented, and not more than six hundred since
the art of making paper out of rags has been known. But people could
write hundreds and hundreds of years before that was invented, and used
almost anything to record the memorable doings of their day--bark of
trees, skins of animals (parchment), "papyrus," 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