I am an optimist. Anyone interested in the future has to be otherwise he would simply shoot himself.

Whether we are based on carbon or on silicon makes no fundamental difference; we should each be treated with appropriate respect.

They had not yet attained the stupefying boredom of omnipotence; their experiments did not always succeed.

In this universe the night was falling; the shadows were lengthening towards an east that would not know another dawn. But elsewhere the stars were still young and the light of morning lingered; and along...

The trouble with cliché’s, some philosopher remarked, probably with a yawn, is that they are so boringly true. But “love at first sight” is never boring.

Personally, I refuse to drive a car – I won’t have anything to do with any kind of transportation in which I can’t read.

But most of the time, with a contented resignation that comes normally to a man only at the end of a long and busy life, he sat before the keyboard and filled the air with...

We want a President who has to be carried screaming and kicking into the White House — but will then do the best job he possibly can, so that he’ll get time off for good...

Many of the fundamental physical constants-which as far as one could see, God could have given any value He liked-are in fact very precised adjusted, or fine-tuned, to produce the only kind of Universe that...

There were, however, a few exceptions.One was Norma Dodsworth, the poet, who had not unpleasantly drunk but had been sensible enough to pass out before any violent action proved necessary. He had been deposited, not...

Those wanderers must have looked on Earth, circling safely in the narrow zone between fire and ice, and must have guessed that it was the favourite of the Sun’s children.

The only way of discovering the limits of the possible is to venture a little way past them into the impossible.

It must be wonderful to be seventeen, and to know everything.

After their encounter on the approach to Jupiter, there would aways be a secret bond between them—not of love, but of tenderness, which is often more enduring.

. . . the newspapers of Utopia, he had long ago decided, would be terribly dull.

Long ago the signalling had become no more than a meaningless ritual, now maintained by an animal which had forgotten to learn and a robot which had never known to forget.

My favourite definition of an intellectual: ‘Someone who has been educated beyond his/her intelligence.[Sources and Acknowledgements: Chapter 19]

..the happy hum of humanity.

Bowman was aware of some changes in his behavior patterns; it would have been absurd to expect anything else in the circumstances. He could no longer tolerate silence; except when he was sleeping, or talking...

Now times had changed, and the inherited wisdom of the past had become folly.

I’m sure the universe is full of intelligent life. It’s just been too intelligent to come here.[IRC discussion at Scifi.com, 1 November 1996]

The person one loves never really exists, but is a projection focused through the lens of the mind onto whatever screen it fits with least distortion.

The confrontation lasted about five minutes; then the display died out as quickly as it had begun, and everyone drank his fill of the muddy water. Honor had been satisfied; each group had staked its...

One of the greatest tragedies in mankind’s entire history may be that morality was hijacked by religion.

Even more alarming were persistent rumors that someone had smuggled an Emotion Amplifier on board ‘Mentor’. The so-called joy machines were banned on all planets, except under strict medical control; but there would always be...

Moses Kaldor had always loved mountains; they made him feel nearer to the God whose nonexistence he still sometimes resented.

As his body became more and more defenseless, so his means of offense became steadily more frightful.

I don’t believe in astrology; I’m a Sagittarius and we’re skeptical.

That requires as much power as a small radio transmitter–and rather similar skills to operate. For it’s the application of the power, not its amount, that matters. How long do you think Hitler’s career as...

Western man had relearned-what the rest of the world had never forgotten-that there was nothing sinful in leisure as long as it did not degenerate into mere sloth.

The rash assertion that “God made man in His own image” is ticking like a time bomb at the foundation of many faiths.

(…)Through the ship’s telescopes, he had watched the death of the solar system. With his own eyes, he had seen the volcanoes of Mars erupt for the first time in a billion years; Venus briefly...

…science fiction is something that could happen – but usually you wouldn’t want it to. Fantasy is something that couldn’t happen – though often you only wish that it could.

But it had been widely argued that advanced intelligence could never arise in the sea; there were not enough challenges in so benign and unvarying an environment.

Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.

What is human memory?” Manning asked. He gazed at the air as he spoke, as if lecturing an invisible audience – as perhaps he was. “It certainly is not a passive recording mechanism, like a...

Yes, it made sense, and was so absurdly simple that it would take a genius to think of it. And, perhaps, someone who did not expect to do it himself.

Science can destroy religion by ignoring it as well as by disproving its tenets. No one ever demonstrated, so far as I am aware, the nonexistence of Zeus or Thor, but they have few followers...

Meteorites don’t fall on the Earth. They fall on the Sun and the Earth gets in the way.” – John W. Campbell

There’s no real objection to escapism, in the right places… We all want to escape occasionally. But science fiction is often very far from escapism, in fact you might say that science fiction is escape...

Though the man-apes often fought and wrestled one another, their disputes very seldom resulted in serious injuries. Having no claws or fighting canine teeth, and being well protected by hair, they could not inflict much...

A faith that cannot survive collision with the truth is not worth many regrets.

Any sufficiently advanced technology is indistinguishable from magic.

Please leave me alone; let me go on to the stars.

It has yet to be proven that intelligence has any survival value.

Just like the cosmonauts and their pee plants, all we have is each other.

. . . Moon-Watcher felt the first faint twinges of a new and potent emotion. It was a vague and diffuse sense of envy–of dissatisfaction with his life. He had no idea of its cause,...

La única posibilidad de descubrir los límites de lo posible es aventurarse un poco más allá de ellos, hacia lo imposible.

But please remember: this is only a work of fiction. The truth, as always, will be far stranger.

1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.2. The only way of discovering the...