PHIL JONES wore a suit that night, so thousands of ex-students of Montgomery Blair High School in Silver Spring knew that something big happened. For class, Phil Jones always wore a sport coat and pullover shirt, never a tie. The only time I ever saw him wear a suit and tie to school was the day after the Kennedy assassination.

"I knew this thing was serious," Jones said as he displayed his new gray suit and vest, "when my wife told me I had to go out and buy a suit, I told her I don't wear suits. And she told me that I'll need a suit eventually, so I might as well get one now!"

This serious happening for Phil Jones, 51, was billed as a retirement dinner by his colleagues Cissie Gieda and Paul Ganz, who invited friends and students of Phil Jones to pay him homage. But the 100 people at the Golden Bull restaurant in Adelphi that night knew it wasn't retirement they were celebrating. They were there to laugh and cry because Phil Jones will never stop hunting the white buffalo.

The old Blair football coach, Vince Pugliese, was in fine form with his raucous jokes. And Dan Haberman and Karl Dydak, recent students of Jones, asked everybody ready to join the next Jones project - he is big on projects - to raise their hands. And after Jones received a caricature from Blair art teacher Lee Klopp, and a memory book from Cissie Gielda, and Paul Ganz told him about the scholarship fund to be established in his name, Jones got up and told a few jokes on his colleagues and ex-students.

"You'll have many, many years of happy retirement," Coach Pugliese kept barking, as if Fate was just a lineman that wasn't working hard enough.

Nobody talked about what was really happening. Nobody talked about the hunt for the white buffalo.

For one week, a year and a half ago, Jones lost sight of the quarry. He had talked about it over a beer at the Zebra Room a few days before this party.

It began in third period at Montgomery Blair in February 1977. Jones had an attack that day in school. He couldn't urinate, and so he went to the hospital. At first the doctors said the obstruction was probably benign, but after two operations they knew it wasn't.

"I broke into a cold sweat. Boy, that's weird. You feel ice cold and sweat is dripping down your face. The doctor said I had six months to two years, and I could tell the doctor expected it to be six months. I felt the lost. I didn't want to see anybody. I just lay there. Then the nurse said I had a visitor. I told her I didn't want a visitor. She said he came all the way from Albuquerque. Alburquerque? Well, I told her," Jones laughed, "that I guess I had to see somebody who came all the way from Alburquerque. It was an old student of mine. Brian O'Neill. I taught him in 1959. He's worked in land-use planning now. Since then I haven't been down about this thing."

Of course, it had to be a student to get him back in the hunt, because many students will tell you that Jones was the best teacher they ever had. And of course, the student to revive him had to come from the West and cross the Rockies, the Mississippi Valley and the Appalachians because Phil Jones believe in the land and always taught that belief.

For 21 years he taught American heritage and geography at Montgomery Blair and he taught it in a special way. No one who had Phil Jones as a teacher remembers the textbooks he used. Jones didn't teach a curriculum, he taught patterns, multiple causes and multiple effects, those things that high-school texts just as soon leave to college, and college texts just as soon leave alone, too. Things like the hogcorn cycle, or why stores in the middle of a block fail more often than stores at the corners.

And he would hammer home loftier lessons of Mahan and sea power, Mumford and technology, De Voto and the patterns of greed and imagination that conquered our continent.

The quintessential Jones was to start with an idea, a small idea, in an out-of-the-way place, and show how it influenced history. But I fall into the student's habits of thinking of former teachers in the past tense.

"I have a great idea for an article," he said this week, "about the importance of Albemarle County, Va., in the development of the country. Thomas Walker, who opened the Cumberland Gap, lived there; Meriwether Lewis and Thomas Jefferson were born there, and they opened the Louisiana Purchase.

"Well, I'll write it if I have time," he said with a laugh.

A laugh is always of part of the essential Phil Jones.

"Once you can laugh at something, you've conquered it. A laugh is a triumph. I'd read sections of Heller's 'Catch 22' to classes to make them laugh. The best classes, the smartest classes could always laugh. I've seen colleagues of mine who'd lose their sense of humor, and teaching would become drudgery and they'd just mark time toward their pensions. At least I don't have to worry about that. I don't even go to the dentist anymore."

But teaching was never the be-all and end-all for Jones. There was his wife and five children and his writing, too: that unpublished novel about a child growing up in the Midwest and West, and many magazine articles, and book introductions and contests entered with mixed results.

"I won a set of encyclopedias for getting first for one story and then two years later I entered again and won third prize and another set of encyclopedias. That year first prize got a trip to Yugoslavia."

More visible were scripts he did for NBC-TV's Explorer Series, "The Big Push West," "Reconstruction" and the "Gilded Age." And he's still writing a book on geographic factors in U.S. history and literature.

"According to the doctors my two years are up in February," Jones says, ""but I think I'm going to beat the two years."

Every summer for many years Jones took a group of area students on a trip across country, out to where he was a boy in Nebraska and Oregon.

"That's the best way to teach! Get kids out there where they can see and hear. Once I asked a kid what he thought of the meadowlark that had been singing all morning, and he said he hadn't noticed it. So I made the kids go out alone a half an hour a day and just listen. Then there was the time when a girl who was going blind came with us. She had 5 percent of her sight left, and as we approached Pike's Peak she was trying to see it and all the other kids tried to describe it to her. She taught them to see."

I aksed the teacher who taught so many students the patterns of life if now he sees pattern emerging, threads being tied together in his own life.

"Yes, I do," he answered, paused and smiled. "I'm reading Moody's 'Life After Life'. If there's anything to it I want to be ready to enjoy it. But I guess what I think is the game as an old man in H. L. Davis' novel 'Beulah Land,' as he died. He was with the woman he'd lived with for many years. He looked up at her and said, 'Never got to hunt for the white buffalo, did we?" I guess it's all about that white buffalo. I never got to hunt."

Jones did express another regret to his wife. Nothing of his was bound in a book, he said, a melancholy thought for a man who had inspired so many students to read books. But on the sly his wife had his autobiographical novel "Searching for a Wind" printed privately. And the dinner to honor Jones ended with him honoring us with copies of his book.

"So there came to Larry one day, buried as he was on obscurity, and reduced to a number on some Army index card, a letter with a picture enclosed. The picture was of Larry and The Horse going past the grandstand in the final stretch of the 440 in the district meet. . . .

"Larry studied himself caught for eternity in the one second of agonizing effort. And there, his profile unmistakable at one side of the picture, was Grandpa. . . .Larry could just imagine what he would say: 'The really important thing about the race,' he would probably say, 'was in your making the effort. Nothing else really mattered.'"