Bucephalus said, “But I have gone as far as I can go. I may no longer be able to protect you from the viscissitudes of chance.”

“That can’t be so, Bucephalus,” said Alexander, impatiently. “Do not quail. Weigh all the variables and arrange to pour into my hands whatever of Earth’s wealth still exists outside it.”

“I don’t think I can, Alexander,” said Bucephalus. “I have discovered a factor in human history that I cannot weigh. It is something completely new that does not fit into any of the cycles.”

“There can be nothing new,” said Alexander, now in a fury. “Do not hang back. I order you to proceed.”

“Very well, then,” said Bucephalus, with a remarkably human sigh.

Alexander knew that Bucephalus was straining at this one last, greatest task, and he was confident that at any moment, it would be accomplished. The world would then be his entirely and through all eternity. “What is this something new?” he asked with a flicker of curiosity.

“Myself,” said Bucephalus, in a whisper. “Nothing like me has ever before exis-”

And before the last syllable could be expressed, Bucephalus went dark as every last chip and circuit within itself fused as a result of his mighty effort to encompass himself as part of history. In the economic and financial chaos that followed, Alexander was wiped out.

Earth regained its liberty-which meant, of course, that there was a certain amount of disorder here and there, but most people considered that a small price to pay.

Dear Mabel,

Well, here we are, as promised. They’ve given us a permit to live in the Valles Marineris, and don’t think we haven’t been waiting for a year and a half because we have. They’re so slow and they keep talking about the capital investment required to make the place livable.

Valles Marineris sounds good as an address, but we just call it the Canyon, and I don’t know why they’re so worried about its being livable. It’s the Martian Riviera, if you ask me.

In the first place, it’s warmer down here than it is in the rest of Mars, a good ten degrees (Celsius) warmer. The air is thicker-thin enough, heaven knows-but thicker and a better protection against ultraviolet.

Of course, the main difficulty is getting in and out of the Canyon. It’s four miles deep in places and they’ve built roads here and there so that you can get down in special mobiles. Getting up and out is more difficult, but with gravity only two-fifths what it is on Earth, it isn’t as bad as it sounds, and they do say they’re going to build elevators that will take us at least partway up and down.

Another problem is, of course, that dust storms do tend to accumulate in the Canyon more than on the ordinary surface, and there are landslides now and then, but heavens, we don’t worry about that. We know where the faults are and where the landslides are likely to occur and no one digs in there.

That’s the thing, Mabel. After all, everyone on Mars lives under a dome or underground, but here in the Canyon, we can dig in sideways, which I understand is much preferable from an engineering standpoint, though I’ve asked Bill not to try to explain it to me.

For one thing, we can heat out some of the ice crystals, so that we don’t have to depend on the government for all the water we need. There is more ice down in the Canyon than elsewhere and, for another, it’s easier to manufacture the air, keep it inside the diggings, and circulate it when you’re in horizontally instead of down vertically. That’s what Bill says.

And I’ve been thinking about it, Mabel. Where’s the need to leave the Canyon, anyway? It’s over three thousand miles long and in the end there are going to be diggings all along it. It’s going to be a huge city, and I’ll bet you most of the population of Mars will end up here. Can’t you see it? There’s to be some kind of maglev rail running the length of the Canyon and communication will be easy. The government ought to put every bit of money it can into developing it. It will make Mars a great world.

Bill says (you know what he’s like-all enthusiasm) that the time will come when they will roof in the whole Canyon. Instead of having air just in separate diggings, and having to put on a spacesuit when you want to travel about, we will have a huge world of normal air and low gravity.

I said to him that the landslides might break the dome and we would lose all the air. He said that the dome could be built in separate sections and that any break would automatically shut off the affected areas. I asked him how much all that would cost. He said, “What’s the difference? It will be done little by little, over the centuries.”

Anyway, that’s his job here, now. He’s got his master’s license as an Areo-engineer, and he’s got to work out new ways to make the Canyon diggings even better. That’s why we got our new place here and it looks as though Mars is going to be our oyster.

We may not live to see it ourselves, but if our great-grandchildren make it to 2140, a century from now, we’ll have a world that may well overshadow Earth itself.

It would be wonderful. We’re very excited, Mabel.

Yours, Gladys.

I am sending this message to Earth in an attempt to warn them about what I feel sure is going to happen, and what must happen. It is sad to think of what lies ahead, so no one wants to talk about it, but someone should, as the people of Earth ought to be prepared.

It is the latter half of the twenty-first century and there are a dozen Settlements in orbit about the Earth. Each is, in its way, an independent little world. The smallest has ten thousand inhabitants, the largest almost twenty-five thousand. I’m sure that all Earthmen know this, but you people are so entangled in your own giant world, that you rarely think of us except as some little inconsequential objects out in space. Well, think of us.

Each Settlement imitates Earth’s environment as closely as it can, spinning to produce a pseudo- gravity, allowing sunlight to enter at some times, and not at others, in order to produce a normal day and night. Each is large enough to give the impression of space within, to have farms as well as factories, to have an atmosphere that can give rise to clouds. There are towns, and schools, and athletic fields.

We have some things that Earth has not. The pseudogravitational field varies in intensity relative to position within each Settlement. There are areas of low gravity, even zero gravity, where we can outfit ourselves with wings and fly, where we can play three-dimensional tennis, where we can have unusual gymnastic experiences.

We also have a true space culture, for we are used to space. Our chief work, aside from keeping our Settlements running efficiently, is to build structures in space for ourselves and for Earth. We work in space, and to be in a spaceship or a spacesuit is second nature to us. Working at zero gravity is something we have done from childhood.

There are also some things Earth has that we do not. We don’t have Earth’s weather extremes. In our carefully controlled Settlements, it never gets too hot or too cold. There are no storms and no unarranged precipitation.

Nor do we have Earth’s dangerous terrain. We have no mountains, no cliffs, no swamps, no deserts, no stormy oceans. And we have no dangerous plants, animals, or parasites. If anything, there are some among us who complain that we are too secure, that there is no adventure-but then our people can always go out into space, and make long trips to Mars and to the asteroids, which you Earthpeople are psychologically unfit to do. In fact, there are plans by some Settlers to set up colonies on Mars and mining bases in the asteroid belt, but it may never come to that, for reasons I will describe.

The Settlements did not spring on humanity unawares. Even a century ago, Gerard O’Neill of Princeton and his students were making initial plans for such new homes for humanity, and science fiction writers had anticipated it even before that.

Oddly enough though, the difficulties that most foresaw turned out to be not those that plagued the Settlements. The expense of building them, the problems of providing an Earth-like environment, the gathering of energy, the matter of protection against cosmic rays were all solved. It was not done easily, but it was done.

The Sun itself supplies all the energy we need, and enough more to export some to Earth. We can grow food easily-more than we need, in fact, so that we can export some to Earth. We have small animals-rabbits, chickens, and so on, that can supply us with meat. We get what material we need from space, not only from the Moon, but from meteoroids and comets that we can trap and exploit. Once we reach the asteroids (if we ever do) we will have a virtually unlimited supply of everything we need.

What bothers us and produces an insuperable problem is something that few people foresaw. It is the difficulty of keeping up a viable ecology. Each Settlement must support itself. It contains people, plants, and animals; it contains air, water, and soil. The living things must multiply and maintain their numbers, but not outpace the ability of the Settlement to support them.

The plants and animals? Well, we control them. We supervise their breeding and we consume any excess. Maintaining the human population at a reasonable level is more difficult. We cannot allow human births to outstrip human deaths, and we keep the number of deaths as low as possible, of course. This makes our culture a nonyouthful one compared to Earth’s. There are few youngsters and a large percentage of those mature and postmature. This produces psychological strains, but there is the general feeling among Settlers that those strains are worth it, since with a carefully controlled population, there are no poor, no homeless, and no helpless.

Again, the water, air, and food must be carefully recycled, and much of our technology is devoted to the distillation of used water, and to the treatment of solid bodily wastes and their conversion to clean fertilizer. We cannot afford to have anything go wrong with our recycling technology, for there is little room for slack. And, of course, even when all goes well, the feeling that we eat and drink recycled materials is a bit unpalatable. All is recycled on Earth, too, but Earth is so large and the natural cycling system so unnoticeable, that Earthpeople tend to be unaware of the matter.

Then, too, there is always the fear that a sizable meteor may strike and damage the outer shell of a Settlement. A bit of matter no larger than a piece of gravel might do damage, and one a foot across would surely destroy any Settlement. Fortunately, the chances for such a misadventure are small and we will eventually learn to detect and divert such objects before they reach us. Still, these dangers weigh upon us, and help mitigate the feeling of over-security that some of us complain about.