Remembering that I'll be dead soon is the most important tool I've ever encountered to help me make the big choices in life. Because almost everything — all external expectations, all pride, all fear of embarrassment or failure - these things just fall away in the face of death, leaving only what is truly important. Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart.

I do not know with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. Letter to Harry S. Truman.

He who is not contented with what he has, would not be contented with what he would like to have.

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

You have enemies? Good. That means you've stood up for something, sometime in your life.

We are what we repeatedly do. Excellence, then, is a habit.

Anyone who has never made a mistake has never tried anything new.

The key to immortality is first living a life worth remembering.

To improve is to change. To be perfect is to change often.

Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for.

A very rich person should leave his kids enough to do anything but not enough to do nothing.

If you love life, don't waste time, for time is what life is made up of.

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

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

Why change the world when we can change ourselves?

History will be kind to me, for I intend to write it.

Innovation is the distinction between a leader and a follower.

For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much - the wheel, New York, wars and so on - whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man - for precisely the same reasons.

A wise man can learn more from a foolish question than a fool can learn from a wise answer.

There is only one good, knowledge, and one evil, ignorance.

The most heinous and the most cruel crimes of which history has record have been committed under the cover of religion or equally noble motives.

Being the richest man in the cemetery doesn't matter to me... Going to bed at night saying we've done something wonderful... that's what matters to me. Summer 1993.

History does not repeat itself, but it rhymes.

I am not an Athenian or a Greek, but a citizen of the world.

Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet.