Quotes from Carl Sagan

Certainly on this planet it is not apparent that there are beings more intelligent than humans, although a case can be made for dolphins and whales, and in fact if humans succeed in destroying themselves with nuclear weapons, a case can be made that ALL other animals are smarter than humans.

Even if the aliens are short, dour, and sexually obsessed—if they're here, I want to know about them.

The major religions on the Earth contradict each other left and right. You can't all be correct. And what if all of you are wrong? It's a possibility, you know. You must care about the truth, right?

Science cuts two ways, of course; its products can be used for both good and evil. But there's no turning back from science.

Scientists make mistakes. Accordingly, it is the job of the scientist to recognize our weakness, to examine the widest range of opinions, to be ruthlessly self-critical. Science is a collective enterprise with the error-correction machinery often running smoothly.

We are a way for the cosmos to know itself

Censoring] knowledge, telling people what they must think and what ideas are impermissible, which lines of evidence may not be pursued, is the aperture to thought police, foolish and incompetent decision-making, and long-term decline.

Man is the matter of the cosmos, contemplating itself.

The impediment to scientific thinking is not, I think, the difficulty of the subject. Complex intellectual feats have been mainstays even of oppressed cultures. Shamans, magicians and theologians are highly skilled in their intricate and arcane arts. No, the impediment is political and hierarchical.

The visions we offer our children shape the future. It matters what those visions are.

The brain is like a muscle. When it is in use we feel very good. Understanding is joyous.

It is the responsibility of scientists never to suppress knowledge, no matter how awkward that knowledge is, no matter how it may bother those in power; we are not smart enough to decide which pieces of knowledge are permissible, and which are not. …

two chimpanzees were observed maltreating a chicken: One would extend some food to the fowl, encouraging it to approach; whereupon the other would thrust at it with a piece of wire it had concealed behind its back. The chicken would retreat but soon allow itself to approach once again--and be beaten once again. Here is a fine combination of behavior sometimes thought to be uniquely human: cooperation, planning a future course of action, deception and cruelty.

I maintain there is much more wonder in science than in pseudoscience. And in addition, to whatever measure this term has any meaning, science has the additional virtue, and it is not an inconsiderable one, of being true.

In that case, on behalf of Earthlife, I urge that, with full knowledge of our limitations, we vastly increase our knowledge of the Solar System and then begin to settle other worlds.

If we know only our own side of the argument, we hardly know even that; it becomes stale, soon learned only by rote, untested, a pallid and lifeless truth.

In good speaking, should not the mind of the speaker know the truth of the matter about which he is to speak?

Hippocrates wrote: "Men think epilepsy divine, merely because they do not understand it. But if they called everything divine which they do not understand, why, there would be no end of divine things.

We tend not to be especially critical when presented with evidence that seems to confirm our prejudices.

All the explanations proposed seem to be only partly satisfactory. They range from massive climatic change to mammalian predation to the extinction of a plant with apparent laxative properties, in which case the dinosaurs died of constipation.

Dear Friend, Just a line to show that I am alive & kicking and going grand. It's a treat.

Would we argue that ten thousand target nuclear warheads are likely to enhance the prospect for our survival? What account would we give of our stewardship of the planet Earth? We have heard the rationales offered by the nuclear superpowers. We know who speaks for the nations. But who speaks for the human species? Who speaks for Earth?

Like other mammals, they are capable of strong emotions. They have certainly committed no crimes. I do not claim to have the answer, but I think it is certainly worthwhile to raise the question: Why, exactly, all over the civilized world, in virtually every major city, are apes in prison?

Everything not forbidden by the laws of nature, he assured her - quoting a colleague down the hall - is mandatory.