“When one door of happiness closes, another opens, but often we look so long at the closed door that we do not see the one that has been opened for us.”

I'm as proud of many of the things we haven't done as the things we have done. Innovation is saying no to a thousand things.

You cannot step twice into the same river, for other waters are continually flowing in.

If you think you're too small to make a difference, try sleeping with a mosquito.

Endure, my heart; you have endured worse than this.

Time you enjoy wasting, was not wasted.

I will build a great wall -- and nobody builds walls better than me.