" conceded Crane, "but it probably is not
universally true."

"Sure not--couldn't be, hardly. No doubt we could find a lot of worlds
inhabited by all kinds of intelligent things--freaks that we can't even
begin to imagine now--but they probably would be occupying planets
entirely different from ours in some essential feature of atmosphere,
temperature, or mass."

"But the Fenachrone world is entirely different," Dorothy argued, "and
they're more or less human--they're bipeds, anyway, with recognizable
features. I've been studying that record with you, you know, and their
world has so much more mass than ours that their gravitation is simply
frightful!"

"That much difference is comparatively slight, not a real fundamental
difference. I meant a hundred or so times either way--greater or less.
And even their gravitation has modified their structure a lot--suppose
it had been fifty times as great as it is? What would they have been
like? Also, their atmosphere is very similar to ours in composition, and
their temperature is bearable. It is my opinion that atmosphere and
temperature have more to do with evolution than anything else, and that
the mass of the planet runs a poor third."

"You may be right," admitted Crane, "but it seems to me that you are
arguing from insufficient premises."

"Sure I am--almost no premises at all. I would be just about as well
justified in deducing the structure of a range of mountains from a
superficial study of three pebbles picked up in a creek near them.
However, we can get an idea some time, when we have a lot of time."

"How?"

"Remember that planet we struck on the first trip, that had an
atmosphere composed mostly of gaseous chlorin? In our ignorance we
assumed that life there was impossible, and didn't stop. Well, it may be
just as well that we didn't. If we go back there, protected as we are
with our rays and stuff, it wouldn't surprise me a bit to find life
there, and lots of it--and I've got a hunch that it'll be a form of life
that'd make your grandfather's whiskers curl right up into a ball!"

"You do get the weirdest ideas, Dick!" protested Dorothy. "I hope you
aren't planning on exploring it, just to prove your point?"

"Never thought of it before. Can't do it now, anyway--got our hands full
already. However, after we get this Fenachrone mess cleaned up we'll
have to do just that little thing, won't we, Mart? As that intellectual
guy said while he was insisting upon