Forget about waiting for Jamie Dimon to stand up for the stock market. The oracle of Omaha has spoken.

Amid the darkest days since the 1987 crash, the American bull—Warren Buffett—has taken the challenge by the horns and declares in an op-ed article in the New York Times today that now is the time to buy American stocks.

Fear has been gripping the market for months, he acknowledges. But that is a signal to buy.

"Fears regarding the long-term prosperity of the nation's many sound companies make no sense," he says. "These businesses will indeed suffer earnings hiccups, as they always have. But most major companies will be setting new profit records five, 10, and 20 years from now."

"Be fearful when others are greedy, and be greedy when others are fearful," is his maxim.

The next few months—and even the next year—may be ugly, he acknowledges. "What is likely, however, is that the market will move higher, perhaps substantially so, well before either sentiment or the economy turns up. So if you wait for the robins, spring will be over."

Buffett makes clear he is talking his own book—his own personal investments, not buying for his holding company Berkshire Hathaway.

While Buffett has become a celebrity and elder statesman in the last two decades—appearing on CNBC, talk shows, and even playing himself on a soap opera—he has rarely made pronouncements on the stock market. His past op-ed articles over the last three decades, in the New York Times and the Washington Post, dealt with issues like corporate accounting, stock options, deposit insurance, soft campaign contributions, the trade deficit, and corporate raiders.

His most famous message on the market was a warning, not an exhortation to invest. In several speeches and an article in Fortune in 1999, Buffett warned about overvalued stocks and the possibility of a bubble. His skepticism, amid the near-universal hype about the internet and technology stocks at that time, is a defining episode in the first authorized biography of Buffett, The Snowball.

And the fact that Buffett chose the sober editorial pages of the New York Times, which have not been as friendly to Wall Street and business, as say the pages of the Wall Street Journal or other publications, speaks volumes.

These are challenging times, and no one is going to listen to another rah-rah, bullish-on-America message that Wall Street firms like Merrill Lynch have been pitching for years. The economy is in a recession, and, yes, it will take time for the government interventions. But what Buffett is saying is this: The American economy has a future. We need to start thinking about it again.