ruins of an earlier cosmos--the crumbs of an exploded world--matter
ejected from the sun--the snow of a nebulous ring--frozen spray from the
fiery surge of a nebula? we cannot tell; but, according to the meteoric
as distinguished from the nebular hypothesis of the solar system, the
sun, planets, and comets, as well as the stars and nebula were all
generated by the clash of meteorites; and not as I have supposed, of
dead globes."

"Which hypothesis do you believe?"

"There may be some truth in both," replied Gazen. "The two processes
might even go on together. What if meteorites are simply frozen nebula?
It is certain that the earth is still growing a little from the fall of
meteoric stones, and that part of the sun's heat comes from meteoric
fuel. Most of it, however, arises from the shrinkage of his bulk. Five
or ten million years ago the sun was double the size he is now. Twenty
or thirty million years ago he was rather a nebula than a sun. In five
or ten million more he will probably be as Jupiter is now--a smoking
cinder."

"And the earth--how long is it since she was crusted over?"

"Anything from ten to several hundred million years. In that time the
stratified rocks have been deposited under water, the land and sea have
taken their present configurations; the atmosphere has been purified;
plants and animals have spread all over the surface. Man has probably
been from twenty to a hundred thousand years or more on the earth, but
his civilization is a thing of yesterday."

"How long will the earth continue fit for life?"