Best 744 quotes of Carl Sagan on MyQuotes

A blade of grass is a commonplace on Earth; it would be a miracle on Mars. Our descendants on Mars will know the value of a patch of green. And if a blade of grass is priceless, what is the value of a human being?

A book is made from a tree. It is an assemblage of flat, flexible parts (still called "leaves") imprinted with dark pigmented squiggles. One glance at it and you hear the voice of another person, perhaps someone dead for thousands of years. Across the millennia, the author is speaking, clearly and silently, inside your head, directly to you. Writing is perhaps the greatest of human inventions, binding together people, citizens of distant epochs, who never knew one another. Books break the shackles of time ― proof that humans can work magic.

A book is proof that humans are capable of working magic.

Accommodation to change, the thoughtful pursuit of alternative futures are keys to the survival of civilization and perhaps of the human species.

A celibate clergy is an especially good idea, because it tends to suppress any hereditary propensity toward fanaticism.

A central lesson of science is that to understand complex issues (or even simple ones), we must try to free our minds of dogma and to guarantee the freedom to publish, to contradict, and to experiment. Arguments from authority are unacceptable.

Across the sea of space, the stars are other suns.

Advances in medicine and agriculture have saved vastly more lives than have been lost in all the wars in history.

After I give lectures-on almost any subject-I am often asked, "Do you believe in UFOs?" I'm always struck by how the question is phrased, the suggestion that this is a matter of belief and not evidence. I'm almost never asked, "How good is the evidence that UFOs are alien spaceships?

A galaxy is composed of gas and dust and stars - billions upon billions of stars. Every star may be a sun to someone.

A general problem with much of Western theology in my view is that the god portrayed is too small. It is a god of a tiny world and not a god of a galaxy much less of a universe.

A googolplex is precisely as far from infinity as is the number 1... no matter what number you have in mind, infinity is larger still.

All civilizations become either spacefaring or extinct.

All inquires carry with them some element of risk. There is no guarantee that the universe will conform to our predispositions.

All of the books in the world contain no more information than is broadcast as video in a single large American city in a single year. Not all bits have equal value.

All of the rocky and metallic material we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interior of a red giant star. We are made of star stuff.

All of us cherish our beliefs. They are, to a degree, self-defining. When someone comes along who challenges our belief system as insufficiently well-based - or who, like Socrates, merely asks embarrassing questions that we haven't thought of, or demonstrates that we've swept key underlying assumptions under the rug - it becomes much more than a search for knowledge. It feels like a personal assault.

All over the world there are enormous numbers of smart, even gifted, people who harbor a passion for science. But that passion is unrequited. Surveys suggest that some 95% of Americans are "scientifically illiterate." That's...the same fraction...of slaves who were illiterate before the Civil War.

A millennium before Europeans were willing to divest themselves of the Biblical idea that the world was a few thousand years old, the Mayans were thinking of millions and the Hindus billions.

A multitude of aspects of the natural world that were considered miraculous only a few generations ago are now thoroughly understood in terms of physics and chemistry.

An atheist has to know a lot more than I know. An atheist is someone who knows there is no god. By some definitions atheism is very stupid.

An atheist is someone who is certain that God does not exist, someone who has compelling evidence against the existence of God. I know of no such compelling evidence. Because God can be relegated to remote times and places and to ultimate causes, we would have to know a great deal more about the universe than we do now to be sure that no such God exists. To be certain of the existence of God and to be certain of the nonexistence of God seem to me to be the confident extremes in a subject so riddled with doubt and uncertainty as to inspire very little confidence indeed.

An atheist is someone who is certain that God does not exist, someone who has compelling evidence against the existence of God. I know of no such compelling evidence.

And after we returned to the savannahs and abandoned the trees, did we long for those great graceful leaps and ecstatic moments of weightlessness in the shafts of sunlight of the forest roof?

A new consciousness is developing which sees the earth as a single organism and recognizes that an organism at war with itself is doomed. We are one planet.

A new consciousness is developing which sees the earth as a single organism and recognizes that an organism at war with itself is doomed. We are one planet. One of the great revelations of the age of space exploration is the image of the earth finite and lonely, somehow vulnerable, bearing the entire human species through the oceans of space and time.

An extraterrestrial being, newly arrived on Earth - scrutinizing what we mainly present to our children in television, radio, movies, newspapers, magazines, the comics, and many books - might easily conclude that we are intent on teaching them murder, rape, cruelty, superstition, credulity, and consumerism. We keep at it, and through constant repetition many of them finally get it.

An organism at war with itself is doomed.

Any civilization that doesn't develop space travel dies.

Any faith that admires truth, that strives to know God, must be brave enough to accommodate the universe.

Any sufficiently crisp question can be answered by a single binary digit-0 or 1, yes or no.

Anything else you're interested in is not going to happen if you can't breathe the air and drink the water. Don't sit this one out. Do something. You are by accident of fate alive at an absolutely critical moment in the history of our planet.

A proclivity for science is embedded deeply within us, in all times, places, and cultures. It has been the means for our survival. It is our birthright. When, through indifference, inattention, incompetence, or fear of skepticism, we discourage children from science, we are disenfranchisin g them, taking from them the tools needed to manage their future.

A religion old or new, that stressed the magnificence of the universe as revealed by modern science, might be able to draw forth reserves of reverence and awe hardly tapped by the conventional faiths. Sooner or later such a religion will emerge.

As agonizing a disease as cancer is, I do not think it can be said that our civilization is threatened by it. ... But a very plausible case can be made that our civilization is fundamentally threatened by the lack of adequate fertility control. Exponential increases of population will dominate any arithmetic increases, even those brought about by heroic technological initiatives, in the availability of food and resources, as Malthus long ago realized.

A single message from space will show that it is possible to live through technological adolescence. . . . It is possible that the future of human civilization depends on the receipt of interstellar messages.

Ask courageous questions. Do not be satisfied with superficial answers. Be open to wonder and at the same time subject all claims to knowledge, without exception, to intense skeptical scrutiny. Be aware of human fallibility. Cherish your species and your planet.

Ask courageous questions. Do not be satisfied with superficial answers.

A stars rich in europium; of distant galaxies analyzed through the collective light of a hundred billion constituent stars. Astronomical spectroscopy is an almost magical technique. It amazes me still. Auguste Comte picked a particularly unfortunate example.

As the ancient myth makers knew, we are children equally of the earth and the sky.

A still more glorious dawn awaits / not a sunrise, but a galaxy-rise / a morning filled with 400 billion suns / the rising of the milky way

At a few hundred kilometers altitude, the Earth fills half your sky, and the band of blue that stretches from Mindanao to Bombay, which your eye encompasses in a single glance, can break your heart with its beauty. Home you think. Home. This is my world. This is where I come from. Everyone I know, everyone I ever heard of, grew up down there, under that relentless and exquisite blue.

A tiny blue dot set in a sunbeam. Here it is. That's where we live. That's home. We humans are one species and this is our world. It is our responsibility to cherish it. Of all the worlds in our solar system, the only one so far as we know, graced by life.

Atoms are mainly empty space. Matter is composed chiefly of nothing.

At the extremes it is difficult to distinguish pseudoscience from rigid, doctrinaire religion.

At the heart of science is an essential balance between two seemingly contradictory attitudes-an openness to new ideas, no matter how bizarre or counterintuitive they may be, and the most ruthless skeptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense.

Avoidable human misery is more often caused not so much by stupidity as by ignorance, particularly our ignorance about ourselves.

Because men, compared to male chimps, have such relatively small testicles (large testicles indicate a species where many males mate, one after the other, with the same female), we might guess that promiscuous societies were uncommon in the immediate human past.

Be grateful everyday for the brief but magnificent opportunity that life provides.

Better by far to embrace the hard truth than a reassuring fable. If we crave some cosmic purpose, then let us find ourselves a worthy goal.