The other day, I found myself rummaging through a closet, searching for my old viola. This wasn’t how I’d planned to spend the afternoon. I hadn’t given a thought to the instrument in years. I barely remembered where it was, much less how to play it. But I had just gotten word that my childhood music teacher, Jerry Kupchynsky — “Mr. K.” to his students — had died.

In East Brunswick, N.J., where I grew up, nobody was feared more than Mr. K. He ran the town’s music department with a ferocity never before seen in our quiet corner of suburbia. In his impenetrably thick Ukrainian accent, he would berate us for being out of tune, our elbows in the wrong position, our counting out of sync.

“Cellos sound like hippopotamus rising from bottom of river,” he would yell during orchestra rehearsals. Wayward violinists played “like mahnyiak,” while hapless gum chewers “look like cow chewing cud.” He would rehearse us until our fingers were callused, then interrupt us with “Stop that cheekin plocking!”

Mr. K. pushed us harder than our parents, harder than our other teachers, and through sheer force of will made us better than we had any right to be. He scared the daylight out of us.

I doubt any of us realized how much we loved him for it.

Which is why, decades later, I was frantically searching for an instrument whose case still bore the address of my college dorm. After almost a half-century of teaching, at the age of 81, Mr. K. had died of Parkinson’s disease. And across the generations, through Facebook and e-mail messages and Web sites, came the call: it was time for one last concert for Mr. K. — performed by us, his old students and friends.

Now, I used to be a serious student. I played for years in a string quartet with Mr. K.’s violin-prodigy daughters, Melanie and Stephanie. One of my first stories as a Wall Street Journal reporter was a first-person account of being a street musician.

But I had given it up 20 years ago. Work and motherhood intervened; with two children and long hours as an editor, there wasn’t time for music any more. It seemed kind of frivolous. Besides, I wasn’t even sure I would know how.

The hinges creaked when I opened the decrepit case. I was greeted by a cascade of loose horsehair — my bow a victim of mites, the repairman later explained. It was pure agony to twist my fingers into position. But to my astonishment and that of my teenage children — who had never heard me play — I could still manage a sound.

It turned out, a few days later, that there were 100 people just like me. When I showed up at a local school for rehearsal, there they were: five decades worth of former students. There were doctors and accountants, engineers and college professors. There were people who hadn’t played in decades, sitting alongside professionals like Mr. K.’s daughter Melanie, now a violinist with the Chicago Symphony Orchestra. There were generations of music teachers.

They flew in from California and Oregon, from Virginia and Boston. They came with siblings and children; our old quartet’s cellist, Miriam, took her seat with 13 other family members.

They came because Mr. K. understood better than anyone the bond music creates among people who play it together. Behind his bluster — and behind his wicked sense of humor and taste for Black Russians — that was his lesson all along.

He certainly learned it the hard way. As a teenager during World War II, he endured two years in a German internment camp. His wife died after a long battle with multiple sclerosis. All those years while we whined that he was riding us too hard, he was raising his daughters and caring for his sick wife on his own. Then his younger daughter Stephanie, a violin teacher, was murdered. After she vanished in 1991, he spent seven years searching for her, never giving up hope until the day her remains were found.

Yet the legacy he had left behind was pure joy. You could see it in the faces of the audience when the curtain rose for the performance that afternoon. You could hear it as his older daughter Melanie, her husband and their violinist children performed as a family. You could feel it when the full orchestra, led by one of Mr. K.’s protégés, poured itself into Tchaikovsky and Bach. It powered us through the lost years, the lack of rehearsal time — less than two hours — and the stray notes from us rustier alums.

Afterward, Melanie took the stage to describe the proud father who waved like a maniac from a balcony in Carnegie Hall the first time she played there. At the end of his life, when he was too ill to talk, she would bring her violin to his bedside and play for hours, letting the melodies speak for them both. The bonds of music were as strong as ever.

In a way, this was Mr. K.’s most enduring lesson — and one he had been teaching us since we were children. Back when we were in high school, Mr. K. had arranged for Melanie and our quartet to play at the funeral of a classmate killed in a horrific car crash. The boy had doted on his little sister, a violinist. We were a reminder of how much he loved to listen to her play.

As the far-flung orchestra members arrived for Mr. K.’s final concert, suddenly we saw her, that little girl, now grown, a professional musician herself. She had never stopped thinking about her brother’s funeral, she told me, and when she heard about this concert, she flew from Denver in the hope that she might find the musicians who played in his honor. For 30 years, she had just wanted the chance to say, “Thank you.”

As did we all.