"Earth has been regarded for centuries as a giant self-regulating machine, absorbing all changes, great and small, and diluting their effects until they become invisible on a global scale. Mankind has taken that stability for granted. Careless of consequences, we have watched as forests were cleared, lakes poisoned, rivers dammed and diverted, mountains leveled, whole plains dug out for their mineral and fuel content. And nothing disastrous happened. Earth tolerated the insults, and always she restored the status quo. Always—until now. Until finally some hidden critical point has been passed. The move away from a steady state is signalled in many ways: by increasing ocean temperatures, by drought and flood, by widespread loss of topsoil, by massive crop failure, and by the collapse of worldwide fishing industries."

"“Lop the top-end tail off the distribution of human intelligence and creativity,” he went on, “and it would make no measurable difference to the population. Only one person in a billion is out beyond the six-sigma level. That’s what we’re talking about here. But eventually those one-in-a-billion make a huge difference. Ninety-five percent of all human progress comes from less than one thousandth of one percent of the population.”"

"“My aunt doesn’t even believe there is a Ship. She says we’ve been here on Pentecost forever.” “What did you tell her?” “Nothing. For someone with that view, logic is irrelevant—she’ll believe what she chooses, regardless of evidence. Her religion says God placed us here on Pentecost, and for her that’s the end of the argument.” “And you?” Peron was aware that she had moved in very close to him. “What do you think?” “You know what I think. I’m cursed with a logical mind, and a lot of curiosity.”"

"Where orbits are wildly varying, life has no chance to develop. Changes are too extreme. Temperatures melt tin, then solidify nitrogen. If it is once established, life is persistent; it can adapt to many extremes. But there is a fragility in the original creation that calls for a long period of tightly-controlled variations."

"The answers come pat and fast. You see, what the downsiders want isn’t an explanation; it’s a catchphrase they can use instead of an explanation."

"I do not like to concatenate implausibilities."

"“It is my personal belief that nothing can exceed light speed,” said Sy at last. “I will mistrust anyone, government or Immortal, man or woman, human or alien, who attempts to tell me otherwise without providing convincing evidence.”"

"That’s what logic says. But I say, phooey, who wants logic? Not you, and not me. We want results."

"When in doubt, follow the money trail. People could lie, motives could be disguised, even acts could be misunderstood. Money was as constant as human nature."

"He had defined intuition for Sondra: it was what remained after all the facts had been forgotten. But intuition could also be something else. Sometimes it was the subconscious mind, establishing deep connections long before the thinking part of the brain could explain them."

"When you got right down to it, every important decision in life was made with inadequate information."

"To a political mind, everything is politics."

"He was still young enough to hate looking like a fool more than anything in the world."

"He had achieved his objective, but his little inside voice would not keep quiet. Too easy, it said, much too easy. When a difficult goal is achieved with no effort, it’s time to be suspicious."

"Not it. He. Bey was sure he would have determined that for himself after a few more seconds. There were a hundred clues as to the innate sex of a form, and most of them had nothing to do with appearance or dress."

"You can learn more about a person by watching them eat one meal than by listening to them speak for a whole day."

"“Hormones are everything, Turpin,” she said to the bird on her shoulder. “Brains are nice, and looks are nice, and logic’s even nicer; but hormones run the show. For everyone, even for me and you.”"

"War was senseless. And yet war came creeping steadily closer."

"They saw every event through the distorting lens of their own paranoia."

"“I think I’ll have a sign made for that far wall,” said Bey at last. “Indeed?” “Yes. It will say, ‘If you have nothing to do, please don’t do it here’.”"

"Sometimes wealth and power merely created the desire for more of the same."

"It’s the usual sensation mongering; the news services will say anything for an effect."

"“Did you do what I asked you to?” “As much as I could. Have you ever tried to brief your boss, without telling her what’s going on?” “A hundred times. It’s the first rule of self-preservation.”"

"The ship climbed steadily and laboriously up, away from the plane of the ecliptic. Finally, the parallax was sufficient to move the planets from their usual apparent positions. Mars, Earth, Venus, and Jupiter all sat in constellations that were no part of the familiar zodiac. Mercury was cowering close to the sun. Saturn alone, swinging out at the far end of her orbit, seemed right as seen from the ship. Bey Wolf, picking out their positions through a viewport, wondered idly how the astrologers would cope with such a situation. Mars seemed to be in the House of Andromeda, and Venus in the House of Cygnus. It would take an unusually talented practitioner to interpret those relationships and cast a horoscope for the success of this enterprise."

"One thing you have to teach the young is that it’s wrong to run away from problems."

"Like many things in life, the problem I had been so sure I could solve proved more difficult than it sounded."

"The Asteroid Belt contains everything from substantial bodies like Ceres, seven hundred and fifty kilometers across, all the way down to house-sized boulders, pebbles, and grains of sand. One good rule of thumb is that for every object of a given size, there will be ten times as many one-third that size."

"That’s the trouble with the younger generation. They don’t understand why a thing can’t be done, so they go ahead and do it."

"The mills of bureaucracy may or may not grind fine, but they certainly grind exceeding slow."

"If I’ve learned one thing wandering around inside and outside the Solar System, it’s this: Nature has more ways of killing you than you can imagine. When you think you’ve learned them all, another one pops up to teach you humility—if you’re lucky. If not, someone else will have to decide what did you in."

"It is remarkable that observation of the faint agglomerations of stars known as galaxies leads us, very directly and cleanly, to the conclusion that we live in a Universe of finite and determinable age. A century ago, no one could have offered even an approximate age for the Universe. For an upper bound, most nonreligious scientists would probably have said “forever.” For a lower bound, all they had was the age of the Earth."

"“It doesn’t make sense,” he said huskily. “Nothing ever does before you understand it, and then it seems obvious.”"

"It’s no surprise that there are people like Anna Griss in the world. There always have been. Go back fifty thousand years, to a time when most of us were just grubbing along, looking for a decent bush of ripe berries or a fresher lump of meat. A few, like McAndrew, were busy inventing language or numbers, or painting the walls of the cave. And some, just a handful but too many in every generation, were seeking an edge over the rest of us: Water access, or mating rules, or restricted entry to heaven. No matter how few they were, Anna Griss would have been one of them."

"You just can’t tell. Brains won’t correlate with appearance."

"And there you had it. Most people hate to learn that they are wrong. Not McAndrew. When he’s proved wrong, he’s ecstatic. It means he’s learned something new, and that’s his main reason for existence."

"I think my inner voices are pretty good when it comes to warning of trouble. The problem is, I don’t always listen to them."

"The first ten-thousandth of a second after the Big Bang is far more interesting that the entire rest of the history of the universe."

"See, everybody looks at the world from his own point of view. I call it the ground state of the resting mind. And your brain does the same thing, left alone it returns to and thinks about what it’s really interested in."

"The laws of probability not only permit coincidences; they absolutely insist on them."

"“I wonder why somebody would go to all that trouble to make a complete fool of himself.” “Come on, Gina, we both know why.” “Oh, I guess you’re right. Money will always do it.” Of course."

"The possible future is not just longer than the past. It is unimaginably longer."

"The more foolproof you think something is, the worse the failure when it happens."

"“Captain Roker, I don’t like your insinuation,” he said. “McAndrew is a physicist—so am I. You may not be smart enough to realize it, but physics is a field of study, not a surgical operation. Castration isn’t part of the Ph.D. Exams, you know.”"

"But maybe we wrongly define the higher human functions. How we think and feel about everything except questions of pure logic is decided maybe five percent in our brains, ninety-five percent in our glands. And how many events in human history have been the result of logical thought? Just try to name one."

"I sometimes think that the only thing in life that I find truly irresistible is the challenge to finagle something that everyone else says can’t be done."

"“Any great thoughts?”… “The younger generation are clearly unfitted to run the world, but one day they are going to do it anyway.”"

"As usual he looked tired, but that was normal. Geniuses worked harder than anyone else, not less hard."

"Unfair to other students? Probably. I was not going to worry about that. Show me a totally impartial teacher, and I’ll show you a robot."

"As the poet laureate of all confidence tricksters and treasure-seekers puts it, we were “given to strong delusion, wholly believing a lie.”"