The Fort Worth Symphony had just finished its traditional playing of The Star-Spangled Banner when the Bass Hall crowd and the musicians began to settle in for what was going to be a concert celebrating the 50th anniversary of the Van Cliburn Competition.What happened next was both stunning and historic.Out onto the stage shuffled the tall, slender and familiar figure of Van Cliburn, assisted by symphony conductor and close friend Miguel Harth-Bedoya. The audience leaped to its feet to applaud the pianist. Some cried out "Whoa!" Others just cried, at what may well be an emotional farewell.How the iconic pianist, who has been gravely ill with advanced bone cancer, managed to appear at the event and deliver a brief but spirited address is a testament to the man who has been delighting crowds and orchestrating breathtaking moments for more than 50 years."He willed himself to do it," said Alann Sampson, the interim president and CEO of the Van Cliburn Foundation who shared with the Star-Telegram how Cliburn's appearance on Thursday night unfolded.It almost didn't happen.During a recent visit with Cliburn, Harth-Bedoya and the pianist had discussed the possibility of Cliburn appearing at the concert. But nothing definite was decided."He'd been looking forward to participating in the 50th anniversary celebration," Sampson said. "We've had several events throughout the year, but this concert was especially important to him." It featured four winners of the Van Cliburn International Piano Competition: Ralph Votapek, who won the first Cliburn in 1962; Andre-Michel Schub, who won in 1981; Alexander Kobrin, Gold Medalist in 2005; and Haochen Zhang, the 2009 winner.But a half-hour before the 7:30 p.m. concert, Harth-Bedoya and Sampson hadn't received word of whether Cliburn was coming for sure. "He is on oxygen and he is very frail," Sampson said. "But he was hoping to make the appearance, as much as possible."At 7:29, Cliburn's car drove up and Sampson, who was at the stage door, sent a text to the Cliburn's artistic manager, who was with Harth-Bedoya. "Miguel came out and helped Van out of the car," she said. "It was very dear."To maintain his classic "tall and ramrod straight" posture, as Star-Telegram reviewer Olin Chism described him in his review, Cliburn had to go on stage without his oxygen. It was a risk, Sampson said, but Cliburn made it through the poignant moment with his signature grace."He just goes out there and delivers an amazing, emotional, powerful speech," Harth-Bedoya said. "No description can do it justice. I didn't know exactly what he was going to say. The only thing he said backstage was that he wanted to thank everybody."Cliburn praised Fort Worth, the orchestra, Harth-Bedoya, Bass Hall and the International Piano Competition that bears his name. After hugging a few people onstage, he made his exit, turning to the audience to tell them, "I'll love you all from the bottom of my heart forever."Cliburn's appearance wasn't just a surprise to the audience. "The musicians did not know," Sampson said. "The musicians were all onstage, and no one saw him come in. ... Mr. Cliburn came around to stage-door right, and stood up, took off his oxygen and walked onstage with Miguel."Paul Unger, assistant principal bass for the symphony, said all of the musicians were "awed and humbled" by the moment."Van's been the spiritual center of classical music in Fort Worth for a very long time," Unger said. "It was really inspiring to be there. I think there was a tear in every musician's eye. It just made the whole evening extra special."Cliburn, who turned 78 in July, has been an international celebrity since he stunned the world in 1958 by winning the first Tchaikovsky International Competition in Moscow. The unlikely triumph at the height of the Cold War vaulted the lanky Texan to a level of stardom rarely achieved by classical musicians, including a ticker tape parade in New York City.In 1962, Cliburn also lent his name to the quadrennial Van Cliburn International Piano Competition, widely considered to be one of the world's finest. He has greeted each of the young performers at the competitions, befriended many, and presented awards to the winners. The next competition will begin in May in Fort Worth.Asked if Thursday night's appearance at Bass Hall was Van's valedictory, Sampson said: "We don't know. ... We have friends from China, New York, Fort Worth asking that question. But we don't have an answer. The doctors don't have an answer."Cliburn is not bedridden, she said, and he has been receiving visitors daily. But she added: "It was an act of great will on his part to walk that 10 steps to the podium."