In the old world, you devoted 30% of your time to building a great service and 70% of your time to shouting about it. In the new world, that inverts.

We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too.

When you are young spend at least 6 months to one year living as poor as you can， owning as little as you possibly can， eating beans and rice in a tiny room or tent， to experience what your “worst” lifestyle might be. That way any time you have to risk something in the future you won’t be afraid of the worst case scenario.

Libraries were full of ideas—perhaps the most dangerous and powerful of all weapons.