It is impossible to predict the future, and all attempts to do so in any detail appear ludicrous within a very few years.

Politics and economics are concerned with power and wealth, neither of which should be the primary, still less the exclusive, concern of full-grown men.

The great problem, it seems, is finding a single person who combines sound scientific knowledge—or at least the feel for science—with a really flexible imagination.

The facts of the future can hardly be imagined ab initio by those who are unfamiliar with the fantasies of the past.

The one fact about the future of which we can be certain is that it will be utterly fantastic.

The speed with which those who once claimed, "It's impossible" can switch to, "I said it could be done all the time" is really astounding.

Mathematics is only a tool, though an immensely powerful one. No equations, however impressive and complex, can arrive at the truth if the initial assumptions are incorrect.

Anything that is theoretically possible will be achieved in practice, no matter what the technical difficulties, if it is desired greatly enough.

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.

Too great a burden of knowledge can clog the wheels of imagination.

Too much imagination is much rarer than too little; when it occurs, it usually involves its unfortunate possessor in frustration and failure—unless he is sensible enough merely to write about his ideas, and not to attempt their realization.

The real future is not logically foreseeable.

One can only prepare for the unpredictable by trying to keep an open and unprejudiced mind—a feat which is extremely difficult to achieve, even with the best will in the world. Indeed, a completely open mind would be an empty one, and freedom from all prejudices and preconceptions is an unattainable ideal.

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

A sane city, designed from the ground up for the convenience of its inhabitants, would be crisscrossed with slowly moving sidewalks at different levels.

Vehicles—except public utility ones—cannot be permitted much longer in urban areas.

The idea of free public transport, though it makes good common sense, will be anathema to a great many people.

The fundamental problem of continuously moving pedestrian conveyors is: how do you get on to them safely?

If private cars are to continue to operate inside the cities, we will have to put all the buildings on stilts so that the entire ground area can be used for highways and parking lots—and even this may not solve the problem.

The ideal moving road would be one that had a smoothly increasing speed gradient from edge to center, so that there were no sudden jumps in velocity.

Looked at dispassionately, [the automobile] is an incredible device, which no sane society would tolerate.

As industry becomes decentralized, as the use of coal for fuel diminishes and nuclear power enables the factories to move nearer to their sources of supply, so the very need for shifting megatons of raw materials over thousands of miles will dwindle away. With it will pass the chief function of the railroad, which has always been the moving of freight, not of passengers.

We will not have conquered the air until we can go straight up and come straight down—as slowly as we please.

The submarine is a much more efficient vehicle than the surface ship, which wasste much of its energy on the production of waves.

Conscious of their earthbound slavery, men have always looked wistfully at birds and clouds, and have pictured the sky as the abode of the gods.

It is a general rule that whenever there is a technical need, something always comes along to satisfy it—or to bypass it.

The first men were nomads; so may be the last, on an infinitely more advanced technical level.

In all the long history of man, ours is the first age with no new frontiers on land or sea, and many of our troubles stem from this fact.

Man's forthcoming escape from Earth, and the crossing of interplanetary space, will trigger a new renaissance and break the patterns into which our society, and our arts, must otherwise freeze.

Civilization cannot exist without new frontiers; it needs them both physically and spiritually. The physical need is obvious—new lands, new resources, new materials. The spiritual need is less apparent, but in the long run it is more important. We do not live by bread alone; we need adventure, variety, novelty, romance.

The creation of wealth is certainly not to be despised, but in the long run the only human activities really worthwhile are the search for knowledge, and the creation of beauty. This is beyond argument; the only point of debate is which comes first.

As the hierarchy of the universe is slowly disclosed to us, we will have to face this chilling fact: if there are any gods whose chief concern is man, they cannot be very important gods.

No nation can afford to divert its ablest men into such essentially non-creative, and occasionally parasitic, occupations as law, advertising, and banking. Nor can it afford to squander indefinitely the technical manpower it does possess.

We are too far out to see the unknown land. It is enough to ride the wave.

Psychologically as well as physically, there are no longer any remote places on Earth. When a friend leaves for what was once a foreign country, even if he has no intention of returning, we cannot feel that same sense of irrevocable separation that saddened our forefathers. We know that he is only hours away by jet liner, and that we have merely to reach for the telephone to hear his voice. And in a very few years… we will be able to see friends on the far side of the Earth as easily as we talk to them on the other side of the town. Then the world will shrink no more, for it will have become a dimensionless point.

It will never be possible to converse with anyone on another planet.

Some people never learn; those who not long ago laughed at the idea of travel to the planets, are now quite sure that the stars will always be beyond our reach. And again they are wrong, for they have failed to grasp the great lesson of our age—that if something is possible in theory, and no fundamental scientific laws oppose its realization, then sooner or later it will be achieved—granted a sufficiently powerful incentive.

All the star-borne colonies of the future will be independent, whether they wish it or not. Their liberty will be inviolably protected by time as well as space.

Space can be mapped and crossed and occupied without definable limit; but it can never be conquered.

Man is the only animal to be troubled by time, and from that concern comes much of his finest art, a great deal of his religion, and almost all his science.

No project which obeys the law of the conservation of energy should be dismissed out of hand.

In this inconceivably enormous universe, we can never run out of energy or matter. But we can all too easily run out of brains.

The invention of the printing press has not made books less valuable, or less appreciated, because they are now among the commonest instead of the rarest of objects. Nor has music lost its charms, now that any amount can be obtained at the turn of a switch. When material objects are all intrinsically worthless, perhaps only then will a real sense of values arise.

A society based on the replicator would be so completely different from ours that the president debate between capitalism and communism would become quite meaningless. All material possessions would be literally as cheap as dirt.

One day our age of roaring factories and bulging warehouses will pass away, as the spinning wheel and the home loom and the butter churn passed before them. And then our descendants, no longer cluttered up with possessions, will remember what many of us have forgotten—that the only things in the world that really matter are such imponderables as beauty and wisdom, laughter and love.

I would define a civilized man as one who can be happily occupied for a lifetime even if he has no need to work for a living.

It is so rare to meet a glimmer of intelligence in what film producers are pleased to call science-fiction movies that one's gratitude tends to overflow.

The whole world of living creatures, with all its wonderful richness and variety, is dominated and controlled by the elementary fact of geometry which states: if you double the size of an object you multiply its area four times—but its volume (and hence weight) eight times.

Dictators are always small people.

A change of size always involves a corresponding change of time rate.

When all men, wherever they may be, have equal access to the same vast communications network, they will inevitably become citizens of the world, and a major problem of the future will be the preservation of regional characteristics of value and interest. There is grave danger of global leveling-down; the troughs in man's cultural heritage must not be filled at the price of demolishing the peaks.

As communications improve, so the need for transportation will decrease. Our grandchildren will scarcely believe that millions once spent hours of every day fighting their way into city offices—where, as often as not, they did nothing that could not have been achieved over telecommunication links.

The business of the future may be run by executives who are scarcely ever in each other's physical presence. It will not even have an address or a central office—only the equivalent of a telephone number. For its files and records will be space rented in the memory units of computers that could be located anywhere on earth: the information stored in them could read off... whenever any of the firm's offices needed it.

The captains of industry of the 21st century may live where they please, running their affairs through computer keyboards and information-handling machines in their homes. Only on rare occasions would there be any need for more of the personal touch then could be obtained via wide-screen full-color TV. The business lunch of the future could be conducted perfectly well with the two halves of the table 10,000 miles apart; all that would be missing would be the handshakes.

Will there be any time to do any work at all on a planet saturated from pole to pole with fine entertainment, first class music, brilliant discussions, superbly executed athletics, and every conceivable type of information service?... We are becoming a race of watchers, not of doers. The miraculous powers that are yet to come may well prove more than our self-discipline can withstand.

I am an optimist; anyone interested in the future has to be.

Probably 99% of human ability has been wholly wasted; even today, those of us who consider ourselves cultured and educated operate for most of our time as automatic machines, and glimpse the profound resources of our minds only once or twice in a lifetime.

Perhaps the most wonderful thing about life is that it works at all, when it has to employ such extraordinary materials, and has to tackle its problems in such roundabout ways.

If there is ever a war between men and machines, it is easy to guess who will start it.