"Well, I suppose you--er--study them. You sit down and--and watch them.
Probably after dark they get up and do something. And of course, in any
case, you can always dissect one and see what he's had for breakfast.
One way and another you get to know things about them."
"They must have a lot of time for thinking," said Celia, regarding my
limpet with her head on one side. "Tell me, how do they know that there
are no men in Mars?"