I came across this article about Buffett in CNN, written by Jason Zweig. Here's some extracts of the article:
In response to a question from Barbara Kiviat of Time on how he and Munger control their emotions, Buffett replied: "[It] comes about from having an investment philosophy grounded in the idea that a stock is a piece of a business. If you look at it that way, there's no reason to get excited whether some analyst is recommending it or the company is splitting the shares two-for-one, or whatever. The only way to drive the extraneous thoughts out of your mind is to have a philosophy. And for us that philosophy comes from Benjamin Graham and The Intelligent Investor, especially chapters 8 and 20. It's not very complicated stuff."
You need a philosophy and the ability to think independently...It doesn't make any difference what other people think of a stock. What matters is whether you know enough to evaluate the business.
You should be able to write down on a yellow sheet of paper, 'I'm buying General Motors at $22, and GM has  million shares for a total market value of $13 billion, and GM is worth a lot more than $13 billion because _______________." And if you can't finish that sentence, then you don't buy the stock.
The key is not to be seduced by crazy ideas, but instead just stick to the fundamentals year after year. Academia doesn't get too interested in us -- we're too simple. What would the professors do? A great many of the formulas [they use to analyze securities and markets] are dead wrong. They exist purely to give the intellectual class something to do. We don't do anything just exercise our intellectual proclivity for mathematical formulas.
There's no reason we should become fearful if a stock goes down. If a stock goes down 50%, I'd look forward to it. In fact, I would offer you a significant sum of money if you could give me the opportunity for all of my stocks to go down 50% over the next month.
In that single sentence Buffett captured the difference between investing and speculating: An investor, like Buffett, wants the price of a stock to fall below the value of its underlying business so he can buy even more and hold for as long as possible. A speculator (like Jim Cramer) only wants the price of a stock to go up, with no regard for the value of the underlying business at all, so he can sell as fast as possible. To the investor, the market's opinions do not matter. To the speculator, they are the only thing that matters.
A Chinese reporter asked whether Berkshire will be buying more stocks in China now that its market has fallen by almost half, and what the next year will hold for Chinese investors. Buffett's answer held a lesson for investors based anywhere. "We're not in the business of forecasting what the market will do in the next year," said Buffett. "But if a market goes down, we like that. There's no way Charlie and I get upset when stocks go down. We like it, because falling prices give us the opportunity to buy more good businesses at better prices."
Read the full article here : http://money.cnn.com/2008/05/05/news/companies/buffet.pm.wrap/