Pierre Boulez, the former principal conductor of the New York Philharmonic who moved between conducting, composition and teaching over a long career that made him one of the leading figures in modern classical music, has died at age 90.

Boulez, who had been unable to conduct recently due to increasing eye problems, died "peacefully" Tuesday at his home in Baden-Baden, Germany, said his assistant Marion Thiem.

Born in Montbrison, France, on March 26, 1925, Boulez initially studied mathematics as a youth before switching to music. He studied harmony at the Paris Conservatory with composer Olivier Messiaen and had lessons from René Leibowitz in the dissonant 20th-century style known as twelve-tone composition. His compositions include the Second Piano Sonata from 1947-48 and Le Marteau Sans Maître (The Hammer Without A Master), a setting of surrealist poetry by René Char for six instruments and alto voice.

He turned more and more from composition to conducting, leading the New York Philharmonic, where he succeeded Leonard Bernstein, and the BBC Symphony Orchestra during the 1970s.

He led Wagner's Ring cycle of operas at the Bayreuth Festival Theatre and also worked with the Chicago Symphony, the Cleveland Orchestra, Orchestre de Paris and the London Symphony Orchestra.

1996

French composer and conductor Pierre Boulez and Canadian folk rock singer Joni Mitchell were awarded Sweden's prestigious Polar Music Prize in 1996. (Reuters )

His recordings won more than 25 Grammys and, among his many honours, he received Canada's Glenn Gould Prize for lifetime service to music in 2002 and Sweden's Polar Music Prize in 1996.

In 1977, he launched IRCAM, a Paris-based institute focused on music, acoustics and electronics.

Cool and contained

Boulez was a cool and contained presence on the podium, preferring a dark business suit and tie to tuxedo and tails, his gestures communicating logic and precision.

Pierre Boulez and Frank Zappa

Pierre Boulez, right, poses with American composer and guitarist Frank Zappa in Paris in 1984, when he directed three Zappa works. (Joel Robine/AFP/Getty Images)

He had a reputation as an uncompromising modernist who rejected easy ways of pleasing audiences.

In a 2010 interview with Philip Clark for classical music publication Gramophone, Boulez described the more conventional music of American composer Aaron Copland as "folklore and dance" and dismissed German composer Paul Hindemith by saying his music "is very well put together, yes" but "says nothing to me."

Yet as a conductor Boulez ranged well beyond the confines of modernism, often favouring Romantic audience favourites such as Bruckner, Mahler and Wagner. For some of his last recordings he chose the lush, moody works of early 20th century Polish composer Karol Szymanovski.

"I may be wrong, but I equate music with culture," he was quoted as saying in the Gramophone interview. "I don't think music is an entertainment product. It's a product of culture — not for marketing, but to enrich lives."

"All these years, I've been trying to convince people that music is not there to please them; it's there to disturb them."

Fans mourn Boulez: composer, conductor, teacher

"Pierre Boulez made French music shine throughout the world. As a composer and conductor, he always wanted to reflect on his era," said French President François Hollande, one of the influential musician's many fans who are mourning him and sharing their favourite works online.

Thiem, Boulez's assistant, said he never married. He is survived by a brother, Roger, and a sister, Jeanne Chevalier, along with several nieces and nephews. Funeral plans were incomplete.

Watch Boulez give a conducting master class (in French) at the Conservatoire de Paris in 2009 in the video below.

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French conductor and composer Pierre Boulez, signals to an orchestra in 1964. (Erich Auerbach/Getty Images)