Carl Sagan

If the greenhouse effect is a blanket in which we wrap ourselves to keep warm, nuclear winter kicks the blanket off.

Carl Sagan

If there is life, then I believe we should do nothing to disturb that life. Mars then, belongs to the Martians, even if they are microbes.

Carl Sagan

If we are to survive, our loyalties must be broadened further, to include the whole human community, the entire planet Earth.

Carl Sagan

In more than one respect, the exploring of the Solar System and homesteading other worlds constitutes the beginning, much more than the end, of history.

Carl Sagan

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.

Carl Sagan

In the vastness of the Cosmos there must be other civilizations far older and more advanced than ours.

Carl Sagan

It goes with a courageous intent to greet the universe as it really is, not to foist our emotional predispositions on it but to courageously accept what our explorations tell us.

Carl Sagan

It is all a matter of time scale. An event that would be unthinkable in a hundred years may be inevitable in a hundred million.

Carl Sagan

It’s been said that astronomy is a humbling and, I might add, a character-building experience.

Carl Sagan

Looking at fires when high, by the way, especially through one of those prism kaleidoscopes which image their surroundings, is an extraordinarily moving and beautiful experience.

Carl Sagan