BOSTON -- Who dunnit? What dunnit? In the unfolding economic mystery, various experts, not one of whom predicted the market's crash, have spent the past days playing detective. They have produced an entire lineup of suspects. The deficit dunnit. The computer dunnit. The interest rates dunnit. The trade imbalance dunnit. Somewhere there's probably a contrarian who insists that the miniskirt dunnit.

But the best and brightest of those seeking clues have said it was ''psychology'' that killed the bull market. ''This summer while the market was rising,'' remarked John J. Phelan Jr., the man who chairs the New York Stock Exchange, ''I'd never seen so many people so antsy in my life.''

In the days since Oct. 19, most financial analysts have turned psychoanalysts. The study of the market has become a study of the collective mind. A study of antsy-ness. Have we gone from morning in America to the morning after? From optimism to pessimism about the future?

Traveling west last week while the market was tumbling south, I kept encountering perfect strangers on airplanes who talked freely, and with a good deal of black humor, about how much money they had lost. The veil of privacy that normally surrounds the subject was lifted. Money had suddenly become a shared, public property.

I met no one who claimed prescience. Only Donald Trump obnoxiously gloated to the public of his street smarts, his Wall Street smarts. The man next to me on a flight out of Minnesota was typical of the irony I heard. With self-deprecating wit, he explained to me how he had prudently kept out of the market until exactly two weeks before the disaster.

At the same time, in all my travels, I encountered no one who was fundamentally surprised. Shocked, yes, but surprised no. It was in the ''psychology'' of the thing. Everyone more or less thought it was coming. Maybe, in a peculiar way, they thought they had it coming.

One traveling companion who had lost three years of profits in eight days put it this way: ''I hate losing money, but it was just paper money. I never thought it was real. I never really earned it.''

I don't want to put too much stock in psychology at this volatile moment. It's not good for the portfolio. But along with the optimism that's a part of the American character, there is also a puritanical streak. Especially about money. Especially about money that hasn't been won by labor. To Rosabeth Kanter, at the Harvard Business School, ''there has always been this psychological tension between Wall Street and Main Street.'' It's one that exists inside our own heads: a tension between ''honest hard work'' and ''getting rich quick.''

To many, the market came to look like an unseemly racetrack frequented by a pin-striped crowd of high-rolling gamblers. Even those who were winning weren't necessarily comfortable with the crowd. Or the climate. They kept an eye on the exit.

In the past few years many of the ''haves'' in this country have come to wonder if they ''have'' it too easy. We have grown uncomfortable with the gap between rich and poor, uneasy with the realization that we're living it up on credit, personally and nationally. And downright queasy about a bull market in the face of all that.

Peter F. Drucker, the 77-year-old professor of the Claremont Graduate School, used a blunt analogy for the Wall Streeters of this era: ''The last two years were just too disgusting a spectacle. Pigs gorging themselves at the trough. . . . You know it won't last.'' For the most part, we did know it wouldn't last. Not surprisingly, the one solace in the down market was the plight of bewildered 28-year-old former hotshots, Drucker's ''pigs.'' The young hustlers had become a symbol of the disorderly upside-down world of the boom. No one was sorry for them. ''What do you call a yuppie stockbroker?'' went the joke: ''Hey, waiter!''

So if psychology dunnit, if it's psychology behind the downward spiral of the past weeks, it's the puritanical side of our nature coming back to the fore. Not just uncertainty, but old-fashioned discomfort about the funny money and the funny economy that helped push the bottom out of the market. And as the poet Joseph Brodsky said when he won the Nobel Prize last week: ''Life has a good deal up its sleeve.''