"Why, that's pretty nice, I suppose. But what's this about the 'enterprise being doomed'?"

" 'Nice', he calls it! Well, my old man says that it is an absolute impossibility to keep a permanent colony on Ganymede. It's a perilous toehold, artificially maintained—those were his exact words—and someday the gadgets will bust and the whole colony will be wiped out, every man jack, and then we will quit trying to go against nature."

We didn't talk any more then as we had to go to class. I told Dad about it that night. "What do you think, George?"

"Well, there is something in what he says——"

"Huh?"

"Don't jump the gun. If everything went sour on Ganymede at once and we didn't have the means to fix it, it would revert to the state we found it in. But that's not the whole answer. People have a funny habit of taking as 'natural' whatever they are used to—but there hasn't been any 'natural' environment, the way they mean it, since men climbed down out of trees. Bill, how many people are there in California?"

"Fifty-five, sixty million."

"Did you know that the first four colonies here starved to death? 'S truthl How is it that fifty-odd million can live here and not starve? Barring short rations, of course."

He answered it himself. "We've got four atomic power plants along the coast just to turn sea water into fresh water. We use every drop of the Colorado River and every foot of snow that falls on the Sierras. And we use a million other gadgets. If those gadgets went bad—say a really big earthquake knocked out all four atomic plants—the country would go back to desert. I doubt if we could evacuate that many people before most of them died from thirst. Yet I don't think Mr. Miller is lying awake nights worrying about it. He regards Southern California as a good 'natural' environment.