Carl Sagan

You mean am I for it or against it? You think this is a key question I'm going to be asked on Vega, and you want to make sure I give the right answer? Okay. Overpopulation is why I'm in favor of homosexuality and a celibate clergy. A celibate clergy is an especially good idea, because it tends to suppress any hereditary propensity toward fanaticism.

Not all birds can fly. What separates the flyers from the walkers is the ability to take off.

We are, in a way, temporary ambulatory repositories for our nucleic acids. This does not deny our humanity; it does not prevent us from pursuing the good, the true and the beautiful. But it would be a great mistake to ignore where we have come from in our attempt to determine where we are going.

I would be very ashamed of my civilization if we did not try to find out if there is life in outer space.

The fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses.

Religions are tough. Either they make no contentions which are subject to disproof or they quickly redesign doctrine after disproof. ... near the core of the religious experience is something remarkably resistant to rational inquiry.

Science is a way of thinking much more than it is a body of knowledge.

Who are we, if not measured by our impact on others?

What an astonishing thing a book is.

For all our conceits about being the center of the universe, we live in a routine planet of a humdrum star stuck away in an obscure corner ... on an unexceptional galaxy which is one of about 100 billion galaxies. ... That is the fundamental fact of the universe we inhabit, and it is very good for us to understand that.

My deeply held belief is that if a god of anything like the traditional sort exists, our curiosity and intelligence is provided by such a God. We would be unappreciative of that gift if we suppressed our passion to explore the universe and ourselves.

We're in very bad trouble if we don't understand the planet we're trying to save.

My view is that if there is no evidence for it, then forget about it. An agnostic is somebody who doesn’t believe in something until there is evidence for it, so I’m agnostic.

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?

Except for fools and madmen, everyone knows that nuclear war would he an unprecedented human catastrophe.

No other planet in the solar system is a suitable home for human beings; it's this world or nothing. That's a very powerful perception.

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 to have a good time, or don't they?

In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.

One trend that bothers me is the glorification of stupidity, that the media is reassuring people it's alright not to know anything. That to me is far more dangerous than a little pornography on the Internet.

All of us cherish our beliefs. They are, to a degree, self-defining. When someone comes along who challenges our belief system as insufficiently well-based - or who, like Socrates, merely asks embarrassing questions that we haven't thought of, or demonstrates that we've swept key underlying assumptions under the rug - it becomes much more than a search for knowledge. It feels like a personal assault.

I am often amazed at how much more capability and enthusiasm for science there is among elementary school youngsters than among college students.