the rock has thus been worn away, then a single day of eternity
will have gone by.

THE SETTING OF THE STAGE

WE live under the shadow of a gigantic question mark.

Who are we?

Where do we come from?

Whither are we bound?

Slowly, but with persistent courage, we have been pushing this question
mark further and further towards that distant line, beyond the horizon,
where we hope to find our answer.

We have not gone very far.

We still know very little but we have reached the point where (with a
fair degree of accuracy) we can guess at many things.

In this chapter I shall tell you how (according to our best belief) the
stage was set for the first appearance of man.

If we represent the time during which it has been possible for animal
life to exist upon our planet by a line of this length, then the tiny
line just below indicates the age during which man (or a creature more
or less resembling man) has lived upon this earth.

Man was the last to come but the first to use his brain for the purpose
of conquering the forces of nature. That is the reason why we are going
to study him, rather than cats or dogs or horses or any of the other
animals, who, all in their own way, have a very interesting historical
development behind them.

In the beginning, the planet upon which we live was (as far as we now
know) a large ball of flaming matter, a tiny cloud of smoke in the
endless ocean of space. Gradually, in the course of millions of years,
the surface burned itself out, and was covered with a thin layer of
rocks. Upon these lifeless rocks the rain descended in endless torrents,
wearing out the hard granite and carrying the dust to the valleys that
lay hidden between the high cliffs of the steaming earth.

Finally the hour came when the sun broke through the clouds and saw how
this little planet was covered with a few small puddles which were to
develop into the mighty oceans of the eastern and western hemispheres.

Then one day the great wonder happened. What had been dead, gave birth
to life.

The first living cell floated upon the waters of the sea.

For millions of years it drifted aimlessly with the currents. But during
all that time it was developing certain habits that it might survive
more easily upon the inhospitable earth. Some of these cells were
happiest in the dark depths of the lakes and the pools. They took root
in the slimy sediments which had been carried down from the tops of the