They didn't understand what they were doing. I'm afraid that will be on the tombstone of the human race.

We think we know what we are doing. We have always thought so.

Exercise invigorates the body and sharpens the mind.

It's hard to decide who's truly brilliant; it's easier to see who's driven, which in the long run may be more important.

Whatever it is you seek, you have to put in the time, the practice, the effort. You must give up a lot to get it. It has to be very important to you. And once you have attained it, it is your power. It can't be given away : it resides in you. It is literally the result of your discipline.

The greatest challenge facing mankind is the challenge of distinguishing reality from fantasy, truth from propaganda. Perceiving the truth has always been a challenge to mankind, but in the information age (or as I think of it, the disinformation age) it takes on a special urgency and importance.

They are focused on whether they can do something. They never think whether they should do something.