Civic-minded tycoons often see it as their duty to reassure the masses in times of financial crisis. It is also in their self-interest, as panicked markets do no good to those whose riches and power depend on stability. I do not believe we are entering another Depression. (In fact I switched about 6 percent of my 401(k) and IRA dough from cash into emerging-market and U.S. stock index funds yesterday.) Nevertheless, there is striking similarity between Warren Buffett's piece in today's NYT and J.D. Rockefeller's soothing utterances from 79 years ago.

John D. Rockefeller, Oct. 30, 1929:

"Believing that fundamental conditions of the country are sound and there is nothing in the business situation to warrant the destruction of values that has taken place on the exchanges during the past week, my son and I have for some days been purchasing sound common stocks. We are continuing and will continue our purchases in substantial amounts at levels which we believe represent sound investment values."

Warren Buffett, Oct. 17, 2008:

I’ve been buying American stocks. This is my personal account I’m talking about, in which I previously owned nothing but United States government bonds... Fears regarding the long-term prosperity of the nation’s many sound companies make no sense. These businesses will indeed suffer earnings hiccups, as they always have. But most major companies will be setting new profit records 5, 10 and 20 years from now...

I don’t like to opine on the stock market, and again I emphasize that I have no idea what the market will do in the short term. Nevertheless, I’ll follow the lead of a restaurant that opened in an empty bank building and then advertised: “Put your mouth where your money was.” Today my money and my mouth both say equities.