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.

I think the discomfort that some people feel in going to the monkey cages at the zoo is a warning sign.

We are like butterflies who flutter for a day and think it is forever.

Centuries hence, when current social and political problems may seem as remote as the problems of the Thirty Years' War are to us, our age may be remembered chiefly for one fact: It was the time when the inhabitants of the earth first made contact with the vast cosmos in which their small planet is embedded.

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.

By looking far out into space we are also looking far back into time, back toward the horizon of the universe, back toward the epoch of the Big Bang.

All colours are arbitrary.