"We are all visitors to this planet. We are here for a short time, and we must make the most of it."

"I think that the human race has a great future ahead of it, if we can just learn to cooperate."

"We are very, very small, but we are profoundly significant."

"I believe that the universe is governed by the laws of science. The laws may have been decreed by God, but God does not intervene to break the laws."

"The human failing I would most like to correct is aggression. It may have had survival advantage in caveman days, to get more food, territory or partner with whom to reproduce, but now it threatens to…"