"There are three kinds of people. One kind is the dumb ones who don't learn. The smart ones who learn from their own mistakes. Very smart ones. But then there are the wise ones, the ones who learn from other people's mistakes."
-- not sure

Several

Ran across some great quotes (and individuals) on Jonathan Stark's web site. Below are some of my favorites:

In times of change, the learners will inherit the world and the learned will find themselves beautifully equipped to deal with a world that no longer exists. - Eric Hoffer

Act as if what you do makes a difference. It does. - William James

There are no secrets to success. It is the result of preparation, hard work, learning from failure - Colin Powell [I continually encounter folks who put in the hard work, but lacking in either preparation or, more importantly, learning from failure... and I'm not innocent either. -jr]

Why do you wake up in the morning and do things? If you can't answer that, you might as well end it now. - Peter Baer

The measure of success is not whether you have a tough problem to deal with, but whether it's the same problem you had last year - John Foster Dulles

A problem well stated is a problem half solved. - Charles F. Kettering

A witty saying proves nothing. - Voltaire

Security is mostly superstition. It doesn't exist in nature. Life is a great adventure or it is nothing. - Helen Keller

I do not know with what weapons World War III will be fought, but World War IV will be fought with sticks and stones. - Albert Einstein

Every man takes the limits of his own field of vision for the limits of the world. - Arthur Schopenhauer

Sometimes you get the best light from a burning bridge. - Don Henley

There is no security on this earth, there is only opportunity. - General Douglas MacArthur

Learn from the mistakes of others. You can’t live long enough to make them all yourself. - Eleanor Roosevelt

Try not to become a man of success but rather to become a man of value. - Albert Einstein

Happiness depends upon ourselves. - Aristotle

In preparing for battle I have always found that plans are useless, but planning is indispensable. - Dwight D. Eisenhower

Always do right. This will gratify some people and astonish the rest. - Mark Twain

It is the mark of an educated mind to be able to entertain a thought without accepting it. - Aristotle

Do what you feel in your heart to be right - for you’ll be criticized anyway. You’ll be damned if you do, and damned if you don’t. - Eleanor Roosevelt

There is one and only one path out of poverty. The one and only path out of poverty is entrepreneurship and business success.

[...]

So yes, some business people are too greedy. Some entrepreneurs don't care about their fellow man. Some people do make their money by dishonest means. But remember, the character quotient is no better on the poor side of the fence.

So if you're prospering by means of an honest enterprise - or if you're struggling to put one together - then you are a hero. The bards and minstrels may not sing songs about you, and your handsome face may never appear on The Apprentice, but what you do every day when you get out of bed is a worthwhile and indeed necessary thing.

Don't ever forget it. What you do matters. A lot. It's worth celebrating and it's HONORABLE.

-- Perry Marshall

"We’re orbiting an exploding star. Lighten up."
--Alan Weiss in I Resemble That Remark

"Businesses have expectations for their traffic and often those expectations are not realistic. We all want results and we want them now but the reality is that the market is going to give us what we earn not what we want. So once we get a visitor to the site how do we earn the goal for the traffic? The simple answer is we earn the result by providing a web experience that takes the visitor from hello to thank you. In between those two is a conversation with the prospect and many web sites fail in managing that conversation."

--Bob Dumouchel in "Life After the First Click"

"He who notices, names, and leverages the most patterns, wins."

--Scott Ginsbert (Hello, my name is Scott! nametag guy)

Every part of your success is dependent upon one individual. You are that individual. You’re in charge. You say when to begin. You’ve got the insight to make the right decisions now. To succeed, you’re going to need that insight, along with courage and conscientiousness. If you’re frightened of making mistakes, you’re sunk. Accept that you’ll make mistakes. Each one has a lesson to be learned.

Michael Eisner, chairman and CEO of Disney, and the man who propelled it to undreamt of success, says, "At a certain level, what we do at Disney is very simple. We set our goals, aim for perfection, inevitably fall short, try to learn from our mistakes, and hope that our successes will continue to outnumber our failures." There’s nothing Mickey Mouse about that kind of philosophy -- because it embraces mistakes as part of the process.

--Jay Conrad Levinson (Guerilla Marketing)