Morality must keep up with technology because if a person is faced with the choice of being moral and dead or immoral and alive, they'll choose life everytime.

It is especially difficult for modern people to conceive that our modern, scientific age might not be an improvement over the prescientific period.

If you gamble long enough, you'll always lose -- the gambler is always ruined.

You think you can destroy the planet? What intoxicating vanity. . . . . We've been residents here for the blink of an eye. If we're gone tomorrow, the earth will not miss us.

We need to get environmentalism out of the sphere of religion. We need to stop the mythic fantasies, and we need to stop the doomsday predictions. We need to start doing hard science instead.

The experience of climbing Kilimanjaro affected me so powerfully that, for a long time afterward, if I caught myself saying, "I'm not a person who likes to do that activity, eat that food, listen to that music," I would automatically go out and do what I imagined I didn't like. Generally I found I was wrong about myself - I liked what I thought I wouldn't like. And even if I didn't like the particular experience, I learned I liked having new experiences.

Safety is the last refuge of the scoundrel!