Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The...

We make our purpose.

Every one of us is, in the cosmic perspective, precious. If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another.

For thousands of years humans were oppressed— as some of us still are— by the notion that the universe is a marionette whose strings are pulled by a god or gods, unseen and inscrutable. Then,...

Humans — who enslave, castrate, experiment on, and fillet other animals — have had an understandable penchant for pretending animals do not feel pain. A sharp distinction between humans and ‘animals’ is essential if we...

If we long for our planet to be important, there is something we can do about it. We make our world significant by the courage of our questions and by the depth of our answers.

It’s a lazy Saturday afternoon, there’s a couple lying naked in bed reading Encyclopediea Brittannica to each other, and arguing about whether the Andromeda Galaxy is more ‘numinous’ than the Ressurection. Do they know how...

In all our searching, the only thing we’ve found that makes the emptiness bearable is each other.

Since, in the long run, every planetary civilization will be endangered by impacts from space, every surviving civilization is obliged to become spacefaring–not because of exploratory or romantic zeal, but for the most practical reason...

The idea that God is an oversized white male with a flowing beard, who sits in the sky and tallies the fall of every sparrow is ludicrous. But if by ‘God,’ one means the set...

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

In the vastness of space and the immensity of time, it is my joy to share a planet and an epoch with Annie.[Dedication to Sagan’s wife, Ann Druyan, in Cosmos]

Except for hydrogen, all the atoms that make each of us up—the iron in our blood, the calcium in our bones, the carbon in our brains—were manufactured in red giant stars thousands of light-years away...

People are not stupid. They believe things for reasons. The last way for skeptics to get the attention of bright, curious, intelligent people is to belittle or condescend or to show arrogance toward their beliefs.

It was difficult to hold Broca’s brain without wondering whether in some sense Broca was still in there—his wit, his skeptical mien, his abrupt gesticulations when he talked, his quiet and sentimental moments.

What an astonishing thing a book is. It’s a flat object made from a tree with flexible parts on which are imprinted lots of funny dark squiggles. But one glance at it and you’re inside...

What a marvelous cooperative arrangement – plants and animals each inhaling each other’s exhalations, a kind of planet-wide mutual mouth-to-stoma resuscitation, the entire elegant cycle powered by a star 150 million kilometers away.

Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home.

Absence of evidence is not evidence of absence.

Our television signals leave this planet and go out into space…the signals spread out from the earth in spherical waves, a little like ripples in a pond. They travel at the speed of light, 186,000...

As science advances, there seems to be less and less for God to do. It’s a big universe, of course, so He, She, or It, could be profitably employed in many places. But what has...

Nevertheless, (Jefferson) believed that the habit of skepticism is an essential prerequisite for responsible citizenship. He argued that the cost of education is trivial compared to the cost of ignorance, of leaving government to the...

The vast distances that separate the stars are providential. Beings and worlds are quarantined from one another. The quarantine is lifted only for those with sufficient self-knowledge and judgment to have safely traveled from star...

Al parecer anhelamos un privilegio, merecido no por nuestros esfuerzos, sino por nacimiento, digamos que por el mero hecho de ser humanos y de haber nacido en la Tierra. Podríamos llamarla la noción antropocéntrica, “centrada...

We are all star stuff.

The Cosmos extends, for all practical purposes, forever. After a brief sedentary hiatus, we are resuming our ancient nomadic way of life. Our remote descendants, safely arrayed on many worlds throughout the Solar System and...

If God is omnipotent and omniscient, why didn’t he start the universe out in the first place so it would come out the way he wants? Why’s he constantly repairing and complaining? No, there’s one...

Present global culture is a kind of arrogant newcomer. It arrives on the planetary stage following four and a half billion years of other acts, and after looking about for a few thousand years declares...

At the heart of science is an essential tension between two seemingly contradictory attitueds–an openness to new ideas, no matter how bizarre or counterintuitive they may be, and the most ruthless skeptical scrutiny of all...

The astonishing fact is that similar mathematics applies so well to planets and to clocks. It needn’t have been this way. We didn’t impose it on the Universe. That’s the way the Universe is. If...

Observation: I can’t see a thing. Conclusion: Dinosaurs.

Sailors on a becalmed sea, we sense the stirring of a breeze.

If it can be destroyed by the truth, it deserves to be destroyed by the truth.

The size and age of the Cosmos are beyond ordinary human understanding. Lost somewhere between immensity and eternity is our tiny planetary home. In a cosmic perspective, most human concerns seem insignificant, even petty. And...

The world is so exquisite, with so much love and moral depth, that there is no reason to deceive ourselves with pretty stories for which there’s little goodevidence.

No question; language can free us of feeling, or almost. Maybe that’s one of its functions – so we can understand the world without becoming entirely overwhelmed by it.

There were many women in the Soviet scientific community, proportionately more so than in the United States. But they tended to occupy menial middle-level positions, and male Soviet scientists, like their American counterparts, were puzzled...

Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value the may have in inspiring us or in exciting our sense of wonder.

Black holes collect problems faster than they collect matter.

Science is not only compatible with spirituality; it is a profound source of spirituality.

There is much that science doesn’t understand, many mysteries still to be resolved. In a Universe tens of billions of light-years across and some ten or fifteen billion years old, this may be the case...

Some 3.6 million years ago, in what is now northern Tanzania, a volcano erupted, the resulting cloud of ash covering the surrounding savannahs. In 1979, the paleoanthropologist Mary Leakey found in that ash footprints –...

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.

Before we invented civilization our ancestors lived mainly in the open out under the sky. Before we devised artificial lights and atmospheric pollution and modern forms of nocturnal entertainment we watched the stars. There were...

The hole in the ozone layer is a kind of skywriting. At first it seemed to spell out our continuing complacency before a witch’s brew of deadly perils. But perhaps it really tells of a...

I’m frequently asked, “Do you believe there’s extraterrestrial intelligence?” I give the standard arguments- there are a lot of places out there, the molecules of life are everywhere, I use the word billions, and so...

Religions are often state-protected nurseries of pseudoscience, although there’s no reason why religions have to play that role. In a way, it’s an artefact from times long gone.

Might it be possible at some future time, when neurophysiology has advanced substantially, to reconstruct the memories or insight of someone long dead?…It would be the ultimate breach of privacy.

The laws of nature cannot be randomly reshuffled at the cusps [of an oscillating universe]. If the universe has already gone through many oscillations, many possible laws of gravity would have been so weak that,...

The chief deficiency I see in the skeptical movement is its polarization: Us vs. Them — the sense that we have a monopoly on the truth; that those other people who believe in all these...