On the morning after the crash, in a macabre touch of programming, Washington listeners of public radio awakened to hear the young Bing Crosby crooning the Depression dirge, "Brother, Can You Spare a Dime?":

Once I built a railroad,

Now it's done --

Brother, can you spare a dime?

Once I built a tower to the sun --

Brick and rivet and lime.

Once I built a tower,

Now it's done --

Brother, can you spare a dime? . . .

To those with long memories, or to students of the past, no explanations were needed for that song's mournful message. Everyone, everywhere, knew that something profound had happened. The bubble had burst. The boom of the '80s was over. So, anyway, it seemed in the frantic, fearful falls of Black Monday, the day that will be forever remembered as the great "Market Meltdown" when half a trillion dollars was wrung out of the markets.

Whether that proves to be so over the long term remains to be seen. Just five years ago, in the depths of the "Reagan recession," the worst since the 1930s, similar gloomy forecasts were made. The Dow Jones industrial averages had then plummeted to the 700s. Experts were issuing predictions of worse to come.

Instead, the market took off like a rocket. For month after month, year after year, records were shattered in the "Reagan recovery." Those who invested in stocks doubled, tripled and then quadrupled original investments. Even after the disastrous free-fall of stock prices this week and last -- a decline that amounted to a loss of 30 percent in stock values, far exceeding the percentage losses recorded in the grim days of October 1929 ushering in the Great Depression -- investors still showed a paper profit nearly double the lows of 1982.

Whether Monday's frightening fall on Wall Street turns out to be only a temporary setback before a long-term comeback or the signal of recession cannot be determined in the present roller-coaster environment. But events this week are certain to have major impact on public attitudes -- and on next year's presidential election.

Two kinds of generalized concerns have emerged from grass-roots voter interviews my Washington Post colleagues David S. Broder, Paul Taylor and I have conducted this year.

Even before this week's crash, people were looking nervously toward Wall Street and wondering aloud whether the boom could last. There was growing apprehension about the economic future. It was common to hear people who are doing well themselves say they fear the country is headed for a recession. A strong sense existed that we were living beyond our means -- personally and nationally -- and were going to pay for it.

A second concern was that we could be stumbling into war in the Middle East, and this belief, coupled with economic doubts, reinforced a more generalized public concern -- the fear that events at home and abroad were teetering out of control.

These concerns were surely intensified by the simultaneous occurrences this week of Iranian and U.S. military strikes in the Persian Gulf and the Wall Street dive. Instead of being reassured, the country's worst fears were heightened.

President Reagan's immediate performance did not help matters.

Instead of directly addressing the nation's concerns, he created a picture of passivity and inaction. Never has his off-hand, aw-shucks, thoughtless manner seemed so inappropriate to the serious issues at hand.

"Maybe some people have seen a chance to grab a profit," he casually remarked, in one of those shouted encounters with reporters while waiting to board a helicopter. This, while the markets were crashing and the country was seeking a reliable appraisal of the situation. Instead, it got Hoover-like words of optimism: "I don't think anyone should panic because all the economic indicators are solid."

He created an even more unfortunate impression with his response to another shouted question, this about what he would tell a mythical old lady who had just lost money in the market. "I don't know of anyone -- are you talking about a specific case?" was the fumbled presidential reply.

Ultimately, the president did signal a welcome, if at first tentative, to dealing cooperatively with congressional leaders on ways to reduce the deficit, and appeared far more conciliatory in emphasizing that approach in the news conference last night. But his leadership style, his handling of crises and his economic and foreign policies are certain to become even greater issues in next year's presidential election.