"The boundary between space and the earth is purely arbitrary. And I'll probably always be interested..." — Carl Sagan

For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.

I've written a number of books that have to do with the evolution of humans, human intelligence, human emotions.

Most of the people that I deal with are human. So I've had a lot of experience with that.

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.