Christopher Foss grew up with Glenn Gould, but never got to say goodbye

"She believed she was falling in love with Glenn Gould."

Christopher Foss shrugs as he utters that sentence as though perplexed, still - more than 40 years later - about a domestic snafu that profoundly affected his family. He is trying to explain the love affair between his mother, painter and sculptor Cornelia Foss, and Mr. Gould, the Canadian pianist who was one of the most famous artists of his time.

The two intended to marry. Ms. Foss is said to have been the most important romantic partner of Mr. Gould's storied and eccentric life, which is the subject of a new documentary, Genius Within: the Inner Life of Glenn Gould . The film, which includes excerpts from Mr. Gould's private diaries and memories from many intimate friends who have never spoken publicly about him, is in select theatres across Canada starting this week after making its debut at the Toronto International Film Festival in the fall.

Mr. Foss, now 52, was 9 at the time his mother left his father, the fam-ous pianist and composer Lukas Foss. Ms. Foss moved to Toronto with her two children in 1968 and stayed for almost five years to be with Mr. Gould before returning to her husband.

She co-operated extensively with Peter Raymont and Michèle Hozer, co-directors of the documentary, but chose not to appear at TIFF out of deference to her spouse, who had died only months earlier at the age of 86. He, too, had condoned the project. The "perfect triangle," as Ms. Foss refers in the film to her passion for Mr. Gould and the love she continued to feel for her estranged husband, was known among their circle of friends and biographers.

But if many brushed off the affair as typical sixties-era rebellious behaviour, the Foss children bore the brunt of the emotional hit and were left with unresolved feelings after Mr. Gould's untimely death at the age of 50 in 1982. That much is obvious in the film, as both Mr. Foss and his younger sister, Eliza, openly talk about their relationship with the musical genius.

"I remember feeling very sad and shocked," Mr. Foss says now of Mr. Gould's death. "There were deep feelings of regret that I had not been able to demonstrate to him that there were feelings there. My sister and I did love him, and didn't want to hurt him, but there was really no other way at the time," he explains, a pained expression on his face.

His father, then the music director of the Buffalo Philharmonic, and Mr. Gould, who lived in Toronto, met in 1962 and had great respect for one another's work. But two years later, Ms. Foss and Mr. Gould had started an affair.

Despite the betrayal, Lukas Foss treated his wife's decision to leave him for Mr. Gould with a show of confident permission. "My father was very shrewd with how he handled things," Mr. Foss says. "When my mother left, she was pulling away in the car, and she said, 'I'm going to divorce you!' And my father said, 'Ach, listen. We Fosses don't divorce. Go and have fun! You'll be back.'"

She drove to Toronto, where she settled into a townhouse with her children. Mr. Gould never lived with them.

"He was prudish about this. He was somehow a little anxious about being viewed as having an affair. It was not so much my mother's instigation. He had rules. My mother went to him after we all had dinner."

Still, the Foss children and their mother were a central focus of his life.

"He was very avuncular, very sweet and kind, and he took an interest in me and my sister. We played board games and took road trips in his Impala to Muskoka and Wawa, Ontario. There is this mythology about Glenn, about him as a demonic musician and it's all about his art, but this is someone who had good fun playing with dogs and children. There was such a streak of normalness and coziness in him. I felt he really loved my mother and very much loved us."

Mr. Gould's eccentricities were also very clear, however.

"I watched him immerse his hands constantly in really hot water. They'd come out beet red. He felt that helped circulation in his fingers, and he wore gloves to protect them." To calm his nerves, "he popped [pills]and then he'd drink gallons of coffee. He ate Arrowroot cookies endlessly and runny scrambled eggs. As a kid, I remember thinking, 'What kind of diet is that?'"

His mother sometimes had to protect her lover from her rambunctious children. "You know how little boys are. I had the urge to climb up on his shoulders at one point, and that was a no-no. My mother rushed over. You don't mess with his skeletal [frame] He was very worried: 'Oh, please, please, don't.' But he was sweet about it, never scolding or imperious, not once."

For all the happiness in those early years of his mother's relationship to Mr. Gould, the children, understandably, had divided loyalties. "There was not a clear break from my father, and, because children need to see their dad, we were brought back almost every weekend. My father took a house in Fort Erie across the border from Buffalo, and the relationship with my father and my mother was of some comfort to me then because I don't think they ever fell out of love."

By the fourth year of their stay in Toronto, Mr. Gould's behaviour changed, causing Ms. Foss to reconsider her plan to marry him.

"He never displayed behaviour in front of me, but later I learned that he displayed paranoia, imagining that someone was spying on him," recalls Mr. Foss, a New York- based writer and separated father of two children. "My mother didn't feel safe and comfortable at some level."

The last time the Foss children saw Mr. Gould was when he travelled to New York to try to win their mother back shortly after they left Toronto. "He wanted to see us all, and she was trying to be nice about it. Eliza and I felt that ultimately we made a choice to be with our father, so it was awkward to see this man who you feel you have betrayed a little."

He shrugs again over the memory that still clearly haunts him.

After that encounter in New York, his mother cut off all contact with Mr. Gould. "And not because Glenn didn't want it. But my mother was really determined to make her marriage work again, and didn't see the point. So it was sad. Eliza and I always imagined that we would see him again."

A decade later, Mr. Gould died following a stroke.