a typical chromosomal DNA molecule in a human being is composed of about five billion pairs of nucleotides… But since there are four different kinds of nucleotides, the number of bits of information in DNA is four times the number of nucleotide pairs. Thus if a single chromosome has five billion (5 X 10^9) nucleotides, it contains twenty billion (2 X 10^10) bits of information… We also see that if more than some tens of billions (several times 10^10) of bits of information are necessary for human survival, extragenetic systems will have to provide them: the rate of development of genetic systems is so slow that no source of such additional biological information can be sought in the DNA.

a typical chromosomal DNA molecule in a human being is composed of about five billion pairs of nucleotides… But since there are four different kinds of nucleotides, the number of bits of information in DNA is four times the number of nucleotide pairs. Thus if a single chromosome has five billion (5 X 10^9) nucleotides, it contains twenty billion (2 X 10^10) bits of information… We also see that if more than some tens of billions (several times 10^10) of bits of information are necessary for human survival, extragenetic systems will have to provide them: the rate of development of genetic systems is so slow that no source of such additional biological information can be sought in the DNA.

Carl Sagan
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If it takes a little myth and ritual to get us through a night that seems endless, who among us cannot sympathize and understand?

Carl Sagan
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Billions of years from now our sun, then a distended red giant star, will have reduced Earth to a charred cinder. But the Voyager record will still be largely intact, in some other remote region of the Milky Way galaxy, preserving a murmur of an ancient civilization that once flourished — perhaps before moving on to greater deeds and other worlds — on the distant planet Earth.

Carl Sagan
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We are a way for the cosmos to know itself

Carl Sagan
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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 of physical laws that govern the universe, then clearly there is such a God. This God is emotionally unsatisfying... it does not make much sense to pray to the law of gravity.

Carl Sagan
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We are star stuff harvesting sunlight.

Carl Sagan
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The Cosmos is all that is or was or ever will be. Our feeblest contemplations of the Cosmos stir us -- there is a tingling in the spine, a catch in the voice, a faint sensation, as if a distant memory, of falling from a height. We know we are approaching the greatest of mysteries.

Carl Sagan, Cosmos
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I worry that, especially as the Millennium edges nearer, pseudoscience and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive. Where have we heard it before? Whenever our ethnic or national prejudices are aroused, in times of scarcity, during challenges to national self-esteem or nerve, when we agonize about our diminished cosmic place and purpose, or when fanaticism is bubbling up around us - then, habits of thought familiar from ages past reach for the controls.The candle flame gutters. Its little pool of light trembles. Darkness gathers. The demons begin to stir.

Carl Sagan, The Demon-Haunted World: Science as a Candle in the Dark
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Arguments from authority carry little weight – authorities have made mistakes in the past. They will do so again in the future. Perhaps a better way to say it is that in science there are no authorities; at most, there are experts.

Carl Sagan, The Demon-Haunted World: Science as a Candle in the Dark
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I don't think science is hard to teach because humans aren't ready for it, or because it arose only through a fluke, or because, by and large, we don't have the brainpower to grapple with it. Instead, the enormous zest for science that I see in first-graders and the lesson from the remnant hunter-gatherers both speak eloquently: 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 disenfranchising them, taking from them the tools needed to manage their future.

Carl Sagan, The Demon-Haunted World: Science as a Candle in the Dark
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Those at too great a distance may, I am well are, mistake ignorance for perspective.

Carl Sagan, Dragons of Eden: Speculations on the Evolution of Human Intelligence
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