Carl Sagan

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.

Probably a dozen times since their death I've heard my mother or father, in an ordinary conversational tone of voice, call my name. They had called my name often during my life with them ... It doesn't seem strange to me.

Science is far from a perfect instrument of knowledge. It's just the best we have.

I hold that popularization of science is successful if, at first, it does no more than spark the sense of wonder.

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.

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.

What does it mean for a civilisation to be a million years old? We have had radio telescopes and spaceships for a few decades; our technical civilisation is a few hundred years old ... an advanced civilisation millions of years old is as much beyond us as we are beyond a bushbaby or a macaque

The suppression of uncomfortable ideas may be common in religion or in politics, but it is not the path to knowledge; it has no in the endeavor of science. We do not know in advance who will discover fundamental insights.

I believe that in every person is a kind of circuit which resonates to intellectual discovery-and the idea is to make that resonance work

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.

We are an intelligent species and the use of our intelligence quite properly gives us pleasure. In this respect the brain is like a muscle. When we think well, we feel good. Understanding is a kind of ecstasy.

Virtually every major technological advance in the history of the human species - back to the invention of stone tools and the domestication of fire - has been ethically ambiguous.

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

Many statements about God are confidently made by theologians on grounds that today at least sound specious. Thomas Aquinas claimed to prove that God cannot make another God, or commit suicide, or make a man without a soul, or even make a triangle whose interior angles do not equal 180 degrees. But Bolyai and Lobachevsky were able to accomplish this last feat (on a curved surface) in the nineteenth century, and they were not even approximately gods.

If you want to save your child from polio, you can pray or you can inoculate....Try science.

In many cultures it is customary to answer that God created the universe out of nothing. But this is mere temporizing. If we wish courageously to pursue the question, we must, of course ask next where God comes from? And if we decide this to be unanswerable, why not save a step and conclude that the universe has always existed?

The politicians and the religious leaders and the weapons scientists have been at it for a long time and they've made a thorough mess of it. I mean, we're in deep trouble.

(When asked merely if they accept evolution, 45 percent of Americans say yes. The figure is 70 percent in China.) When the movie Jurassic Park was shown in Israel, it was condemned by some Orthodox rabbis because it accepted evolution and because it taught that dinosaurs lived a hundred million years ago-when, as is plainly stated at every Rosh Hashonhan and every Jewish wedding ceremony, the Universe is less than 6,000 years old.

It means nothing to be open to a proposition we don't understand.

The size and age of the Cosmos are beyond ordinary human understanding. Lost somewhere between immensity and eternity is our tiny planetary home.

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.