Lyndon Johnson greatly admired what he called "can do" people. So I was only half joking when I suggested to Ellsworth Bunker over lunch in Santo Domingo in 1965 that if he managed to resolve the Dominican Republic's civil war, the president would send him next to Vietnam. Bunker chuckled enigmatically, something he did a lot in his business, which was diplomatic troubleshooting for his government.

But he did bring off a Dominican settlement that has given that once tormented country almost two decades of democratic practice and relative tranquillity. And Johnson did send him to Saigon as the American ambassador for six anguishing years. That bad ending never shook the devotion to duty that led Bunker to turn away from private business and take up the practice of diplomacy at age 57.

Nothing ever did, and that's why watching him at work at some of the dozen or so diplomatic assignments he undertook over nearly 30 years was one of those extra dividends you get now and again in the course of covering the diplomatic scene. It was not just that he was extraordinarily good at what he did. That was the point rightly made in the eulogies and obituaries when he died last week at age 90.

Partly it was his proof that the practice of diplomacy rarely fits the stereotype of striped- pants cookie pushers, nit-picking and double- talking and dissembling to no firm purpose. Well, perhaps he did fit the striped-pants bit -- caricatured it almost, with his tall, trim figure, impeccable tailoring, measured words and unflappable inscrutability.

But his public service demolishes the rest of that stereotype. At a time when U.S. foreign policy in the hands of Ronald Reagan and Co. seems dead in the water almost everywhere you look, it also says a lot about what it takes to move diplomacy.

I am not talking just about those positive qualities of character that made Bunker so effective: high intelligence, unquestioned integrity, infinite patience, self-effacing modesty, level temperament. Rather I have in mind the baggage he didn't bring with him to ambassadorial posts or bargaining tables -- political partisanship, for one thing, or ideological frenzy for another.

Now you could say that's nothing special. Partisanship and ideology have their inevitable place in foreign policy. Diplomatic troubleshooters are supposed to be executors of policy more than formulators of it, and certainly not philosophers. But when that's said, Bunker's performance over the years would still define a significant difference between the way foreign policy has been conducted in the past and the manner and atmosphere in which it is conducted by the Reagan administration.

Bunker worked for every president from Truman to Jimmy Carter -- Republicans and Democrats, liberals and conservatives. It is hard to imagine anyone with that sort of curriculum vitae passing a Reagan White House loyalty test.

You could imagine Ellsworth Bunker as U.S. ambassador to the United Nations if he could have found time to squeeze it into his schedule, and he would have been good at it. But you cannot imagine him on the podium at a Republican convention flailing the Democrats while claiming to be one of them and also still holding the job of U.N. ambassador. He had a different sense of the meaning of bipartisanship and also of propriety.

Perhaps nothing better illustrates the difference defined by Bunker's record than the one occasion on which his sense of sound policy and the best interests of the United States collided head-on with Ronald Reagan's. The Panama Canal Treaty, which Bunker brought to a successful conclusion in partnership with Sol Linowitz, was systematically assailed and nearly sabotaged by a conservative opposition led by Reagan. Not being one to stand on false American pride, Bunker could see clearly the potential threat to American security if the canal were left to boil.

The rightness of that judgment ought to be better understood by Reagan than by almost anybody. Panama would not be the invaluable resource it now is for the Reagan policy in Central America had Ellsworth Bunker not seen his duty as he saw it.

Some have said that in Vietnam he was too duty-bound. Bunker simply said he thought the policy he inherited in Saigon would work and that he was wrong about that. But unlike a lot of others who were wrong, he cared enough about the consequences to attend post-mortem seminars on Vietnam; to be an early prominent supporter of the Vietnam War Memorial; to be engaged in his last years in trying to write something about what he had learned.

He called himself "an old-fashioned patriot." But he was from Vermont, and he didn't go in much for chest-thumping or flag-waving or talking a lot about it. He just did a lot about it.