"Every sunset is a reminder that the canvas of tomorrow is painted with the actions of today."

"The pursuit of excellence requires knowing that every failure is just a stepping stone to greatness."

"The glow of one warm thought is to me worth more than money."

"The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants."

"A man's friendships are, like his will, invalidated by marriage - but they are also no less invalidated by the marriage of his friends."

"Each morning sees some task begin,  Each evening sees it close; Something attempted, something done,  Has earned a night's repose."

"I have a private plane. But I fly commercial when I go to environmental conferences."

"I don't pretend to understand the Universe - it's a great deal bigger than I am."