These are scary times. Including President Obama's $787 billion stimulus package, the total tally of projected government outlays now exceeds $10 trillion.

Even more frightening: Many economic experts doubt that this increased spending will have the positive impact that the politicians intend. And the public's confidence in Treasury Secretary Tim Geithner is fading fast.

Why? Bank of America (NYSE: BAC) and Citigroup (NYSE: C) may be insolvent. AIG (NYSE: AIG) is using federal bailout dollars to finance bonus payments to its executives. TARP funds recipient JPMorgan Chase (NYSE: JPM) plans to construct "the premier corporate aircraft hangar on the eastern seaboard."

And I haven't even touched on the shaky status of Eastern European banks, the sinking Japanese economy, or rising unemployment rates in China.

I admit, with all of the negative news coming in, it's difficult to see any semblance of a silver lining. But as a natural contrarian, I have to wonder: What if it's not as bad as everyone thinks?

The power of positive thinking
Right now, we don't know whether our economy faces a return to depression-like conditions. But Markel (NYSE: MKL) Chief Investment Officer Tom Gayner recently pointed out that "the stock market isn't waiting to find out."

The market already assumes that we're headed for a worst-case scenario -- but if it's not as bad as everyone thinks, there's opportunity there.

And Gayner agrees. "The low expectations and low valuations of equity prices might make for a pleasant surprise over the next decade," he said.

What is the nature of this opportunity?
Let's dissect Gayner's prediction -- because there are a few interesting takeaways.

First of all, he thinks of investment returns in terms of decades, not days or weeks. This probably helps explain why he consistently outperforms the short-term-oriented market.

Second, this has little to do with a market bottom, which Gayner isn't calling. He even acknowledges that the U.S. might enter another depression. But -- for the first time in 18 months -- he has begun buying stocks because he believes that today's prices are excellent even considering that risk.

If the doomsday crowd is correct and the U.S. does enter a nasty, prolonged depression, Gayner may lose a little capital, but it's unlikely he'll suffer significant losses, precisely because of those prices. And if the economic forecast isn't as dire as those negative Nancies believe, Gayner will probably be richly rewarded.

The upshot? The key to successful investing isn't buying shares of the world's greatest companies, or the market's cheapest fare. It's buying shares of great companies when they trade at a significant discount to their intrinsic value. Continued...