“If we want our species to survive in the long term, human beings cannot afford to stop reaching for the stars.”

“The selective voluntary blindness of human beings allows them to ignore the moral consequences of their choices. It has been one of the species' most valuable traits, in terms of the survival of any particular human community.”

“Since, in the long run, every planetary civilization will be endangered by impacts from space, every surviving civilization is obliged to become spacefaring--not because of exploratory or romantic zeal, but for the most practical reason imaginable: staying alive... If our long-term survival is at stake, we have a basic responsibility to our species to venture to other worlds.”

“As we cannot afford to squander our natural resources of minerals, food, and beauty, so we cannot afford to discard any human resources of brains, skills, and initiative, even though it is women who possess them...a woman is just as much an ordinary human being as a man, with the same individual preferences, and with just as much right to the tastes and preferences of an individual.”

“Although failure is a great teacher, we cannot afford the time to learn from our failures. Human societies cannot be subjected to such a process.”

“Our humanity consists in the fact that we do more than survive, that a great part of what we do confers no survival benefit in terms presumably salient from the Pleistocene point of view.”