e scientists seemed to need stressing the word "natural"--Eden
was more favorable to easy human life than Earth!

Cal leaned forward. Here was the spot where some student or apprentice
might distinguish himself by asking an embarrassing question or so. Say
the range of easily possible conditions on any given planet was a scale
ten miles in length. Then that area on the scale where man could exist
without artificial aids would still be less than a hair's breadth. And
now to find a planet more nearly perfect for man than the one on which
he evolved....

Or were the students considering this too obvious to mention? He decided
to nudge them a little. Sometimes a discussion of the too obvious
brought out things not obvious at all.

"How frequently," he asked, when Hayes had cut him in, "do we find a
mass revolving in such a manner that its poles revolve at right angles
to its forward revolution, so there is no real pole?"

"It requires near-perfect roundness, and an even distribution of land
and water masses, such as we have on Ceti II," the first astrophysicist
answered.

"How frequently do we find that?" Cal repeated.

"I know of no other," the astrophysicist replied shortly.

"Any evidence of tampering with those ocean currents to get them flowing
so beneficially?" Cal asked.

"None yet discovered," an oceanographer cut in.

Well, at least he hadn't stated with positiveness that there hadn't been
and couldn't be. But an anthropaleontologist inserted himself and
spoiled the effect of open-mindedness.

"There is definitely no life form on Eden with sufficient intelligence
for that," the man said, "nor has there ever been. Such a feat would
require enormous engineering works. Such works under the ocean would be
matched by comparable works on land, and would therefore show up in our
aerial surveys, however ancient and overgrown."

Cal sighed softly to himself. The human kind of civilization, yes, that
would have left traces. But what of some other kind? Perhaps a deep-sea
kind that had never come out upon the land? Never mind the arguments
that such a civilization could not have developed--that was looking at
it from the human point of view again. Had man grown so accustomed to
not finding comparable intelligence anywhere in the universe he had
begun to discount, or forget, there could be?

The review went on and on. The zoologist sketched in the prevalent
animals and fish forms, showed there was nothing in land