Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. That's relativity.

Speak only if it improves upon the silence.

Live as if you were to die tomorrow. Learn as if you were to live forever.

Life is like riding a bicycle. To keep your balance you must keep moving.

The world is a dangerous place to live, not because of the people who are evil, but because of the people who don't do anything about it.

There are many causes I would die for. There is not a single cause I would kill for.

The secret to creativity is knowing how to hide your sources.

Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution.

Science without religion is lame, religion without science is blind.

You should be the change that you want to see in the world.

It takes 20 years to build a reputation and five minutes to ruin it. If you think about that, you'll do things differently.

It has become appallingly obvious that our technology has exceeded our humanity.

The United States invariably does the right thing, after having exhausted every other alternative.

Seven social sins: politics without principles, wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, and worship without sacrifice.

Education is the kindling of a flame, not the filling of a vessel.

There is no way to peace; peace is the way.

If you think a thing is impossible, you'll make it impossible.

It does not matter how slowly you go so long as you do not stop.

All warfare is based on deception.

If we knew what we were doing, it wouldn't be called research, would it?

To study and not think is a waste. To think and not study is dangerous.

George W. Bush has gathered around him upper-crust C-students who know no history or geography.

If I should ever die, God forbid, let this be my epitaph:
THE ONLY PROOF HE NEEDED
FOR THE EXISTENCE OF GOD
WAS MUSIC

Religion is regarded by the common people as true, by the wise as false, and by rulers as useful.

I love deadlines. I like the whooshing sound they make as they go by.