TREVIZE WAS surrounded by the tameness of Gaia. The temperature, as always, was comfortable, and the air moved pleasantly, refreshing but not chilling. Clouds drifted across the sky, interrupting the sunlight now and then, and, no doubt, if the water vapor level per meter of open land surface dropped sufficiently in this place or that, there would be enough rain to restore it.

The trees grew in regular spacings, like an orchard, and did so, no doubt, all over the world. The land and sea were stocked with plant and animal life in proper numbers and in the proper variety to provide an appropriate ecological balance, and all of them, no doubt, increased and decreased in numbers in a slow sway about the recognized optimum. -As did the number of human beings, too.

[...]

On Gaia, houses tended to be simple. With the all-but-complete absence of violent weather of any kind, with the temperature mild at all times in this particular latitude, with even the tectonic plates slipping smoothly when they had to slip, there was no point in building houses designed for elaborate protection, or for maintaining a comfortable environment within an uncomfortable one. The whole planet was a house, so to speak, designed to shelter its inhabitants.

[...]

[Bliss speaking:] I/we/Gaia hide nothing, and we tell no lies. An Isolate - an individual in isolation-might tell lies. He is limited, and is fearful because he is limited. Gaia, however, is a planetary organism of great mental ability and has no fear. For Gaia to tell lies, to create descriptions that are at variance with reality, is totally unnecessary.

[...]

"The whole is greater than the sum of the parts, in other words."

"Exactly. You have grasped the basic justification of Gaia's existence. You, as a human individual, are composed of perhaps fifty trillion cells, but you, as a multicellular individual, are far more important than those fifty trillion as the sum of their individual importance."

[...]

"Don't sneer," said Bliss. "You value every mineral crystal in your bones and teeth and would not have one of them damaged, though they have no more consciousness than the average rock crystal of the same size."

[...]

"Suppose we imagine single-celled organisms with a human level of consciousness and with the power of thought and imagine them faced with the possibility of becoming a multicellular organism. Would not the single-celled organisms mourn their loss of individuality, and bitterly resent their forthcoming enforced regimentation into the personality of an overall organism? And would they not be wrong? Could an individual cell even imagine the power of the human brain?"

[...]

Bliss sighed. "Actually, there's a saying of ours that goes: `When Gaia eats Gaia, there is neither loss nor gain.' It is no more than a transfer of consciousness up and down the scale. Whatever I eat on Gaia is Gaia and when much of it is metabolized and becomes me, it is still Gaia. In fact, by the fact that I eat, some of what I eat has a chance to participate in a higher intensity of consciousness, while, of course, other portions of it are turned into waste of one sort or another and therefore sink in the scale of consciousness."

She took a firm bite of her food, chewed vigorously for a moment, swallowed, and said, "It represents a vast circulation. Plants grow and are eaten by animals. Animals eat and are eaten. Any organism that dies is incorporated into the cells of molds, decay bacteria, and so on-still Gaia. In this vast circulation of consciousness, even inorganic matter participates, and everything in the circulation has its chance of periodically participating in a high intensity of consciousness."

"All this," said Trevize, "can be said of any world. Every atom in me has a long history during which it may have been part of many living things, including human beings, and during which it may also have spent long periods as part of the sea, or in a lump of coal, or in a rock, or as a portion of the wind blowing upon us."

"On Gaia, however," said Bliss, "all atoms are also continually part of a higher planetary consciousness of which you know nothing."

To ANYONE who has been in space and experienced its changelessness, the real excitement of space flight comes when it is time to land on a new planet. The ground speeds backward under you as you catch glimpses of land and water, of geometrical areas and lines that might represent fields and roads. You become aware of the green of growing things, the gray of concrete, the brown of bare ground, the white of snow. Most of all, there is the excitement of populated conglomerates; cities which, on each world, have their own characteristic geometry and architectural variants.

"I neither admire nor condemn. Superstition always directs action in the absence of knowledge. The Foundation believes in the Seldon Plan, though no one in our realm can understand it, interpret its details, or use it to predict. We follow blindly out of ignorance and faith, and isn't that superstition?"

[...]

"I'm not at all sure of that. The point is, though, that we don't know how psychohistory works at all."

"I don't know how that computer works, but I know it works."

"That's because others know how it works. How would it be if no one knew how it worked? Then, if it stopped working for any reason, we would be helpless to do anything about it. And if psychohistory suddenly stopped working-"

Pelorat said, "You know what that reminds me of? -Pardon me, Bliss, for interrupting, but it so fits that I can't resist telling you right now before I forget. There's an old creation myth I once came across; a myth in which life was formed on a planet and consisted of only a limited assortment of species, just those useful to or pleasant for humanity. The first human beings then did something silly-never mind what, old fellow, because those old myths are usually symbolic and only confusing if they are taken literally-and the planet's soil was cursed. `Thorns also and thistles shall it bring forth to thee,' is the way the curse was quoted though the passage sounds much better in the archaic Galactic in which it was written. The point is, though, was it really a curse? Things human beings don't like and don't want, such as thorns and thistles, may be needed to balance the ecology."

Bliss smiled. "It's really amazing, Pel, how everything reminds you of a legend, and how illuminating they are sometimes. Human beings, in terraforming a world, leave out the thorns and thistles, whatever they may be, and human beings then have to labor to keep the world going. It isn't a self-supporting organism as Gaia is. It is rather a miscellaneous collection of Isolates and the collection isn't miscellaneous enough to allow the ecological balance to persist indefinitely. If humanity disappears, and if its guiding hands are removed, the world's pattern of life inevitably begins to fall apart. The planet unterraforms itself."

"Just before Giskard's end, he conceived of a robotic law that superseded even the first. We called it the 'Zeroth Law' out of an inability to think of any other name that made sense. The Zeroth Law is: `A robot may not injure humanity or, through inaction, allow humanity to come to harm.' This automatically means that the First Law must be modified to be: 'A robot may not injure a human being, or, through inaction, allow a human being to come to harm, except where that would conflict with the Zeroth Law.' And similar modifications must be made in the Second and Third Laws."

Trevize frowned. "How do you decide what is injurious, or not injurious, to humanity as a whole?"

"Precisely, sir," said Daneel. "In theory, the Zeroth Law was the answer to our problems. In practice, we could never decide. A human being is a concrete object. Injury to a person can be estimated and judged. Humanity is an abstraction. How do we deal with it?"

"I don't know," said Trevize.

"Wait," said Pelorat. "You could convert humanity into a single organism. Gaia."

"That is what I tried to do, sir. I engineered the founding of Gaia. If humanity could be made a single organism, it would become a concrete object, and it could be dealt with. It was, however, not as easy to create a superorganism as I had hoped. In the first place, it could not be done unless human beings valued the superorganism more than their individuality, and I had to find a mind-cast that would allow that. It was a long time before I thought of the Laws of Robotics."

"Ah, then, the Gaians are robots. I had suspected that from the start."

"In that case, you suspected incorrectly, sir. They are human beings, but they have brains firmly inculcated with the equivalent of the Laws of Robotics. They have to value life, really value it. -And even after that was done, there remained a serious flaw. A superorganism consisting of human beings only is unstable. It cannot be set up. Other animals must be added-then plants-then the inorganic world. The smallest superorganism that is truly stable is an entire world, and a world large enough and complex enough to have a stable ecology. It took a long time to understand this, and it is only in this last century that Gaia was fully established and that it became ready to move on toward Galaxia-and, even so, that will take a long time, too. Perhaps not as long as the road already traveled, however, since we now know the rules."

[...]

Trevize frowned. "How do you decide what is injurious, or not injurious, to humanity as a whole?"

"Precisely, sir," said Daneel. "In theory, the Zeroth Law was the answer to our problems. In practice, we could never decide. A human being is a concrete object. Injury to a person can be estimated and judged. Humanity is an abstraction. How do we deal with it?"

"I don't know," said Trevize.

"Wait," said Pelorat. "You could convert humanity into a single organism. Gaia."

"That is what I tried to do, sir. I engineered the founding of Gaia. If humanity could be made a single organism, it would become a concrete object, and it could be dealt with. It was, however, not as easy to create a superorganism as I had hoped. In the first place, it could not be done unless human beings valued the superorganism more than their individuality, and I had to find a mind-cast that would allow that. It was a long time before I thought of the Laws of Robotics."

"Ah, then, the Gaians are robots. I had suspected that from the start."

"In that case, you suspected incorrectly, sir. They are human beings, but they have brains firmly inculcated with the equivalent of the Laws of Robotics. They have to value life, really value it. -And even after that was done, there remained a serious flaw. A superorganism consisting of human beings only is unstable. It cannot be set up. Other animals must be added-then plants-then the inorganic world. The smallest superorganism that is truly stable is an entire world, and a world large enough and complex enough to have a stable ecology. It took a long time to understand this, and it is only in this last century that Gaia was fully established and that it became ready to move on toward Galaxia-and, even so, that will take a long time, too. Perhaps not as long as the road already traveled, however, since we now know the rules."

"Die? Can a machine die?"

"I can cease to exist, sir. Call it by whatever word you wish. I am old. Not one sentient being in the Galaxy that was alive when I was first given consciousness is still alive today; nothing organic; nothing robotic. Even I myself lack continuity."

"In what way?"

"There is no physical part of my body, sir, that has escaped replacement, not only once but many times. Even my positronic brain has been replaced on five different occasions. Each time the contents of my earlier brain were etched into the newer one to the last positron. Each time, the new brain had a greater capacity and complexity than the old, so that there was room for more memories, and for faster decision and action. But-"

"But?"

"The more advanced and complex the brain, the more unstable it is, and the more quickly it deteriorates. My present brain is a hundred thousand times as sensitive as my first, and has ten million times the capacity; but whereas my first brain endured for over ten thousand years, the present one is but six hundred years old and is unmistakably senescent. With every memory of twenty thousand years perfectly recorded and with a perfect recall mechanism in place, the brain is filled. There is a rapidly declining ability to reach decisions; an even more rapidly declining ability to test and influence minds at hyperspatial distances. Nor can I design a sixth brain. Further miniaturization will run against the blank wall of the uncertainty principle, and further complexity will but assure decay almost at once."

Pelorat said, "Tortoises are cold-blooded. Terminus doesn't have any, but some worlds do. They are shelled creatures, very slow-moving but long-living.”

"Well, then, isn't it better to be a human being than a tortoise; to move quickly whatever the temperature, rather than slowly? Isn't it better to support high-energy activities, quickly contracting muscles, quickly working nerve fibers, intense and long-sustained thought-than to creep slowly, and sense gradually, and have only a blurred awareness of the immediate surroundings? Isn't it?"

"Granted," said Trevize. "It is. What of it?"

"Well, don't you know you must pay for warm-bloodedness? To maintain your temperature above that of your surroundings, you must expend energy far more wastefully than a tortoise must. You must be eating almost constantly so that you can pour energy into your body as quickly as it leaks out. You would starve far more quickly than a tortoise would, and die more quickly, too. Would you rather be a tortoise, and live more slowly and longer? Or would you rather pay the price and be a quick-moving, quick-sensing, thinking organism?"