Carl Sagan citations

Extraordinary claims require extraordinary evidence.
en
Citation presque identique à Extraordinary claims require extraordinary proof. de Marcello Truzzi, co-fondateur du Committee for Skeptical Inquiry.
Cosmos, 1980

[In Pseudoscience] hypothesis are often framed precisely so that they are invulnerable to any experiment that offers a prospect of disproof, so even in principle they cannot be invalidated. Practitioners are defensive and wary. Skeptical scrutiny is opposed. When the pseudoscientific hypothesis fails to catch fire with scientists, conspiracies to suppress it are deduced.
en
The Demon-Haunted World (1995)

You are made of a hundred trillion cells. We are, each of us, a multitude.
en
Cosmos, 1980

Sometimes [Pseudoscience] is a kind of halfway house between old religion and new science, mistrusted by both.
en
The Demon-Haunted World (1995)

We are like butterflies who flutter for a day and think it is forever.
en
Cosmos, 1980

99 per cent of the Earth's atmosphere is of biological origin. The sky is made by life.
en
Cosmos, 1980

Source: Billions & Billions: Thoughts on Life and Death at the Brink of the Millennium

This is a paraphrase of Sagan quoting Thomas Carlyle: "A sad spectacle. If they be inhabited, what a scope for misery and folly. If they be not inhabited, what a waste of space."
Sagan delivered this quote during the symposium on "Life Beyond Earth and the Mind of Man", held at Boston University (20 November 1972), published in Life Beyond Earth and the Mind of Man (1973) edited by Richard Berendzen; Life Beyond Earth and the Mind of Man (1975) National Archives video http://www.youtube.com/watch?v=cQeOp7a8QMI
Misattributed
Source: Contact

Source: Cosmos (1980), p. 193
Contexte: We embarked on our journey to the stars with a question first framed in the childhood of our species and in each generation asked anew with undiminished wonder: What are the stars? Exploration is in our nature. We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars.

Source: Broca's Brain: Reflections on the Romance of Science

Carl Sagan on The Tonight Show with Johnny Carson (full interview, May 20th, 1977)
Others

Source: The Demon-Haunted World : Science as a Candle in the Dark (1995), Ch. 1 : The Most Precious Thing, p. 12
Source: The Demon-Haunted World: Science as a Candle in the Dark

Source: Pale Blue Dot: A Vision of the Human Future in Space (1994), p. 8, Supplemental image at randi.org http://www.randi.org/images/122801-BlueDot.jpg
Contexte: Consider again 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 aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar", every "supreme leader", every saint and sinner in the history of our species lived there — on a mote of dust suspended in a sunbeam.
The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.
Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.
The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.
It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

The Varieties of Scientific Experience: A Personal View of the Search for God (2006)
Contexte: The amount of organic matter that could have been produced in the first few hundred million years of Earth history was sufficient to have produced in the present ocean a several-percent solution of organic matter. This is just about the dilution of Knorr's chicken soup, and not that different from the composition either. And chicken soup is widely known to be good for life.

Source: Pale Blue Dot: A Vision of the Human Future in Space (1994), p. 8, Supplemental image at randi.org http://www.randi.org/images/122801-BlueDot.jpg
Contexte: Consider again 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 aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar", every "supreme leader", every saint and sinner in the history of our species lived there — on a mote of dust suspended in a sunbeam.
The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.
Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.
The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.
It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.

Source: Contact (1985), Chapter 24 (p. 431)
Contexte: The universe was made on purpose, the circle said. In whatever galaxy you happen to find yourself, you take the circumference of a circle, divide it by its diameter, measure closely enough, and uncover a miracle — another circle, drawn kilometers downstream of the decimal point. There would be richer messages farther in. It doesn't matter what you look like, or what you're made of, or where you come from. As long as you live in this universe, and have a modest talent for mathematics, sooner or later you'll find it. It's already here. It's inside everything. You don't have to leave your planet to find it. In the fabric of space and in the nature of matter, as in a great work of art, there is, written small, the artist’s signature. Standing over humans, gods, and demons, subsuming Caretakers and Tunnel builders, there is an intelligence that antedates the universe.

Martin Rees — Sagan refers to this quote in The Demon-Haunted World (1995) (see above)
Misattributed
Source: Cosmos

Source: Contact

Sometimes attributed to Contact (1985), but the quote does not appear in that book.
It appears attributed to Sagan in Judson Poling's 2003 book "Do Science and the Bible Conflict?", but without source.
Misattributed
Source: Via Google Books https://books.google.com/books?id=Ondv5WzhYYYC&pg=PA21&dq=Sagan

[citation needed]
Others

Source: Contact (1985), Chapter 14 (p. 231, quoting George Santayana)

This phrase was created by reporter Sharon Begley in the end of a 1977 Newsweek article with an extended profile of Carl Sagan. It was a final conclusion about Sagan's work and the topic of hypotethical extra-terrestrial life forms. "Quote Investigator" http://quoteinvestigator.com/2013/03/18/incredible/
Misattributed

Source: Cosmos (1980), p. 339

Source: Cosmos

Source: The Demon-Haunted World: Science as a Candle in the Dark

Source: Cosmos (1980), p. 218

7 min 25 sec
Back reference to UFO abduction claims
Cosmos: A Personal Voyage (1990 Update), Encyclopedia Galactica [Episode 12]
Contexte: For all I know we may be visited by a different extraterrestrial civilization every second Tuesday, but there's no support for this appealing idea. The extraordinary claims are not supported by extraordinary evidence.

Source: Contact (1985), Chapter 24 (p. 430)

Source: Cosmos (1980), p. 4