?"

"I don't know," she said. "Only every now and then I find myself thinking
the most _obvious_ thoughts."

"We all do," I answered, as I stroked my limpet gently. The noise of our
conversation had roused it, but a gentle stroking motion (I am told by
those to whom it has confided) will frequently cause its muscles to
relax. "The great thing is not to speak them. Still, you'd better tell me
now. What is it?"

"Well," she said, her cheeks perhaps a little pinker than usual, "I was
just thinking that life was very wonderful. But it's a _silly_ thing to
say."

"It's holiday time," I reminded her. "The need for sprinkling our remarks
with thoughtful words like 'economic' and 'sporadic' is over for a bit.
Let us be silly." I scratched in the rock the goal to which I was urging
my limpet and took out my watch. "Three thirty-five. I shall get him
there by four."

Celia was gazing at two baby fishes who played in and out a bunch of
sea-weed. Above the seaweed an anemone sat fatly.

"I suppose they're all just as much alive as we are," she said
thoughtfully. "They marry"--I looked at my limpet with a new
interest--"and bring up families and go about their business, and it
all means just as much to them as it does to us."

"My limpet's business affairs mean nothing to me," I said firmly. "I am
only wrapped up in him as a sprinter."

"Aren't you going to try to move him again?"

"He's not quite ready yet. He still has his suspicions."

Celia dropped into silence. Her next question showed that she had left
the pool for a moment.

"Are there any people in Mars?" she asked.

"People down here say that there aren't. A man told me the other day that
he knew this for a fact. On the other hand, people in Mars know for a
fact that there isn't anybody on the Earth. Probably they are both
wrong."

"I should like to know a lot about things," sighed Celia. "Do you know
anything about limpets?"

"Only that they stick like billy-o."

"I suppose more about them _is_ known than that?"

"I suppose so. By people who have made a specialty of them. For one who
has preferred to amass general knowledge rather than to specialize, it is
considered enough to know that they stick like billy-o."

"You haven't specialized in anything, have you?"

"Only in wives."

Celia smiled and went on. "How do you make a specialty of limpets?"

"Well, I suppose you--er--study them. You sit down and--and watch them.
Probably after dark they get