“Can you account for that mystery?”

“No.  Science is bound in honour, no doubt, to explain all it can without calling in a special act of creation; but the origin of life and intelligence seems to go beyond it, so far.  Spontaneous generation from dead matter is ruled out of court at present.  We believe that life only proceeds from life.  As for the hypothesis that meteoric stones, the ‘moss-grown fragments of another world’ may have brought life to the earth, I hardly know what to think of it.”

“Has life ever been found on a meteoric stone?”

“Not that I know.  Carbon, at all events in the state of graphite and diamond, has been got from them.  They arc generally a kind of slag, containing nodules or crystals of iron, nickle, and other metals, and look to me as if they had solidified from a liquid or vapour.  Are they 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?”

“Perhaps five or ten million years.  The entire solar system is gradually losing its internal heat, and must inevitably die of sheer inanition.  The time is coming when the sun will drift through space, a black star in the midst of dead worlds.  Perhaps the system will fall together, perhaps it will run against a star.  In either case there would probably be a ‘new heaven and a new earth.’”

“Born like a phoenix from the ashes of the old,” said I, feeling the justice of the well-worn simile.