At breakfast, in the cushioned splendor of Dallas' Adolphus Hotel, a young black man in a conservatively tailored navy blue pin-striped suit, with vest, was discussing business with a young black woman. She was equally well groomed and wearing what critics might call her dress-for-success suit.

Others, less critical, and perhaps possessed of a broader view, might see in that scene affirmation of a great American success story. And so it was.

As the appropriately deferential white waiters took their orders chosen from the impressively expensive menu (their breakfast bill would come to about $20), they kept up a quiet stream of conversation. It was all about business; no social small talk here. They spoke about markets and investments and "pools of capital." Although much of it sounded like jargon to the reportorial eavesdropper at the adjoining table, obviously their words held great meaning for them.

They were making it and, seemingly, taking it all for granted. So were the others in that pleasant room. It was all so ordinary.

Now it so happens that the page one story that attracted my greatest attention that morning bore the headline: "Poverty Rate Rose to 15% in '82, Highest Level Since Mid-1960s." The story described the Census Bureau's finding that the number of Americans officially classified as poor now stands at the highest level since 1965 at the start of Lyndon B. Johnson's War on Poverty.

It also reported that blacks were bearing by far the heaviest burden. Three times as many blacks are living in poverty as whites today. The figures for children are even worse: nearly half of all black children in America are living in poverty.

When I left the hotel and headed off for a round of interviews, I drove past a long line of blacks--men, women and teen-agers--sitting idly by the wall of a downtown office building. The statistics in the news had just come to life.

What had not been highlighted in the news was the evidence of dramatic change in the lives of the other blacks that I had just witnessed in the hotel. They were poles apart, but part of the same story. Perhaps nowhere are those lines of national change more sharply drawn than here.

For a nation that historically has concerned itself much more with its present and future than its past, we have been forced of late to engage in an unusual amount of retrospection. This year has been filled with memorable anniversaries of events that signaled dramatic change for the nation. We find ourselves in the unaccustomed position of looking backward. We are taking stock of ourselves whether we like it or not.

Last March marked the 50th anniversary of Franklin D. Roosevelt's coming to power, carrying with him the New Deal policies that altered American life irrevocably. This month brings the 20th anniversary of Martin Luther King's March on Washington, a symbolic action that touched a moral chord in the country and helped forge the forces that shattered the old society that had kept the American races segregated by law and custom.

November will be the 20th anniversary of John F. Kennedy's assassination here in Dallas, an event that ushered in an era of instability in U.S political life and a series of violent shocks that struck the nation at home and abroad.

In some ways, Dallas is a good touchstone for examining where the nation now stands in this entirely different and even more complex time of the 1980s. For Dallas, perhaps more than any other major city, has undergone a stunning reversal in the way it is viewed, and quite probably in the way it actually is.

To most Americans today Dallas brings to mind the name of a TV soap opera celebrating success, huge fortunes and glamour. Its association with the death of a president is, when remembered at all, merely a happenstance.

Yet before the Kennedy assassination, and for some time after, Dallas was synonymous with political extremism, racial prejudice and a sort of ultraright-wing mentality that easily contributed to many of the lunatic-fringe conspiracy theories that sprang up from the American far left and far right.

Dallas was the place where the Texan, Lyndon Johnson, was jostled and his wife spat at when they entered the lobby of the Adolphus Hotel for a political gathering. Dallas was where Adlai E. Stevenson, that liberal intellectual of mild demeanor, had so unpleasant an experience from a similar encounter that he warned Kennedy about coming here. Dallas was where a former Army general, Edwin A. Walker, came to marshal support against desegregation and to sound the alarm about communists in high places nationally.

Whether Dallas ever deserved that reputation for extremism is beside the point. It had it, and the Kennedy assassination reinforced it.

All that, happily, is long in the past. The Dallas of today is a jewel of a city, gracious, cultured, full of charm and highly cosmopolitan. It stands as an example of the best kinds of American success: a magnet for the energetic and industrious, a place in which imagination has free rein and talent is both attracted and rewarded, and a city that pays attention to the kinds of graces that make a community worth living in.

And it is also a place where racial progress undeniably has occurred, as witness the scene in the Adolphus Hotel of today.

The point is not to romanticize Dallas or to pretend the millennium has arrived in human relations or in racial and economic progress, here or anywhere else. But to see Dallas 20 years after King's march and Kennedy's death is to see a stronger community and country, one that has survived its problems and progressed in ways almost unimaginable before.

That is why the evidence, both statistical and visual, official and personal, of growing disparities between haves and have-nots, of more for some and less for others, is especially dismaying. Any stock-taking of the country's condition now has to take into account not only the successes but those failures.

The lines are lengthening between economic groups in America, including lines between blacks themselves. Those that are doing well are doing better than ever. Those that are slipping back into poverty are in even worse positions than before. As Arthur Miller said in his memorable play about Willy Loman, "Death of a Salesman," attention must be paid.