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 SaganAnything else you're interested in is not going to happen if you can't breathe the air and drink the water. Don't sit this one out. Do something. You are by accident of fate alive at an absolutely critical moment in the history of our planet.
Carl SaganIn a complex universe, in a society undergoing unprecedented change, how can we find the truth if we are not willing to question everything and to give a fair hearing to everything?
Carl Sagan