he spray was warm against their faces, almost as warm as the night
wind.

"Tell me," she said. "You know what really happened, don't you?"

"I think so. I can't really be sure."

They paused on the low ledge where he had stood earlier and watched
the girls gather their data for the reports. At their feet the waves
washed up to the edges of the tide pools, eddying into and out of them
softly. The water looked dark and cold, but they knew that it too was
warm.

"There've been lots of changes, and they all fit a pattern," he said.
"The temperature. The difference in salt content in the water. The
higher tides. Those things could happen for several reasons. But
there's only one explanation for the other changes, the ones I found
on the star charts."

She waited. The water lapped in and out, reaching almost to where they
stood.

"The Earth rotates faster now," he said. "And the stars are nearer.
Much nearer than they were."

"Isn't that impossible?"

"How do we know? We exceeded the speed of light. Who could say what
continuum that might have put us in? I remember an analogy I read
once, in a layman's book on different theories of space-time. '--The
future and the past, two branches of a hyperbola, each with the speed
of light as its limit--'"

"You mean," she whispered, "that we're not in the future at all? We're
in the past--the far past--before there was any life on Earth?"

* * * * *

He looked down at the pools of water at their feet, the lifeless water
that according to all their old discarded theories should have been
teeming with life. He nodded slowly and lifted the glass cylinder he
had brought from the ship and stared at it.

"That bottle," she whispered. "You filled it with bacteria, didn't
you?"

He nodded again.

"You're mad, Hugh. You can't mean that _that bottle_ is the origin of
life on Earth! You can't."

"Maybe this isn't our Earth, Nora. Maybe there are thousands of
continuums and thousands of Earths, all waiting for a ship to land
someday and give them life."

Slowly he unstoppered the cylinder and knelt down at the water's edge.
For a minute he paused, wondering if there were other continuums or
only this one, wondering just how deep the paradox lay. Then he tipped
the bottle up and poured, and the liquid from the cylinder ran down
into the tide pools and eddied there and was lost in the liquid of the
ocean. He poured until the bottle was empty and a