ON FRIDAY, A man named Sweeney walked into the law office of Allard K. Lowenstein and shot him dead. Lowenstein was 51 years old. He has three children and a former wife and several friends and they will all tell you the same thing about him: he mattered.

He mattered in Mississippi and he mattered in New York politics and he mattered in the U.S. Congress and in southern Africa and in the National Student Association, but he mattered most -- at least for me -- when he stopped Lyndon Johnson cold in New Hampshire. It was 1968, and Allard K. Lowenstein had set out to end the war in Vietnam.

I know that one man is not supposed to be able to do that. I know that historians debate whether even heroes --emperors, generals -- control events or whether it is the other way around. I know a teacher who thinks that the correct answer to the question "who discovered America" is "the Nina, the Pinta and the Santa Maria." Allard Lowenstein would not have liked that teacher.

Lowenstein helped organize something called the New York coalition for a Democratic Alternative. It was dubbed the Dump Johnson Movement and it was given no chance of succeeding. No one thought Al Lowenstein could succeed. No one but Lowenstein.That proved in the end to be more than enough.

In 1968, I was a graduate student. In 1968, I was also a member of the United States Army Reserve and bitterly opposed to the war in Vietnam. I'd already decided that if called to fight, I would not, I would go to some other country -- Canada, Sweden. I had told my parents this and they had said, simply, that they understood.

Lowenstein worked near where I lived. At night, I would walk my dog and see the lights burning late. I looked up the stairs and thought about going in, but every time I backedout. It was foolish. It was senseless. Johnson would win a second term. The war would go on and on and no one, especially me, could do anything about it. Later, I went up to New Hampshire. I went to write aboutthe primary, Eugene McCarthy's campaign, as a student. I already knew, of course, how Lowenstein had gone to Robert Kennedy and asked him to runagainst Johnson and how Kennedy anguished, had finally turned him down. In January of that year, at the Commonwealth Club of San Francisco, Kennedy had in fact endorsed Johnson. c

Lowenstein then went to McCarthy. McCarthy also said no, muting that along the way to a maybe. McCarthy also went west -- to Berkeley across the bay from San Francisco. There he gave his standard antiwar speech, but this time called for the resignation of Secretary of State Dean Rusk. The kids went wild. McCarthy became hopeful. He declared for the presidency and Al Lowenstein, working hard once again, cajoled him into that race in New Hampshire.

Much later, of course, Lowenstein would become something of a celebrity and everyone would have his story. He would call in the middle of the night and come over to sleep. He was always on the go, sleeping in his clothes, a kind of hobo of lost causes. Friends who were in South Africa, for instance, were not surprised when Lowenstein dropped in on them in their hotel, asking only if he could use the shower. He stayed for awhile and left. He was wearing dungarees and a New York Yankees baseball jacket.

But on election day in New Hampshire, Allard Lowenstein was not yet a celebrity. That day, he got into hiswhite Mustang for the drive from Manchester to Concord. He sat in theback and talked with me while a student volunteer drove. It was beginning to snow, but Lowenstein wanted to make the trip anyway. He was going to see the student volunteers. He wanted to make sure they didn't flag on this last day. He was going to see a kid named Sam Brown.

We arrived in Concord as the snow was beginning to tell. Lowenstein flew into action. He cajoled the kids to work harder. He went from one to another, talking to them as they madetheir last minute get-out-the-vote calls from little pine stalls. He was a bundle of energy, a short man with hair combed forward, strong and kind always distracted.

After exhorting the students to even greater efforts, Lowensein returned to Manchester. In the evening, the results started to come in and pandemonium broke loose. McCarthy waswinning. People cried and people laughed and finally, they called for Allard Lowenstein to say something.

Lowenstein stood in the glow of the television lights, a little man, strangely shy, and he said that McCarthy's victory prove that the system worked. He made it sound like it would all have happened without Allard K. Lowenstein but that is not the case. A couple of thousand people could tell you, but the whole nation ought to know.

He mattered.