Nikolaus Harnoncourt, 86, Austrian conductor

Nikolaus Harnoncourt stepped down from the podium last year in the same manner that characterized his work as one of the world's famous conductors. With style, but without fanfare.

"Dear public," he wrote Dec. 5. "My physical strength orders me to cancel my future plans." Describing the synergy between him and the audience as leading to an "unusually deep relationship," he said his goodbyes in eight lines in an open letter, simply, elegantly and without pathos.

Mr. Harnoncourt died Saturday of an undisclosed illness, in the village of St. Georgen in Attergau, west of Salzburg, less than three months after taking his last bow. He was 86.

His wife, Alice Harnoncourt, didn't give a cause, saying only that her husband "passed away peacefully, surrounded by his family."

Born into a lineage that included some of Europe's most aristocratic families, Mr. Harnoncourt was also part of Austria's musical nobility, with mastery that put him on the level of other great postwar Austrian conductors Herbert von Karajan, Karl Boehm and Carlos Kleiber.

His concern for historical detail was legendary. He often distributed his own material to orchestras, adding expression marks on how to create more authentic or refined interpretations, aiming to erase what he called "traditionally traded" mistakes. Adding in period instruments as well as tempi and dynamics discarded by modern performances, Mr. Harnoncourt broke through in the 1970s from relative obscurity with a series of celebrated performances of Monteverdi and Mozart.

He thought of his conducting as alive and romantic, not a relic of history.

"I have always hated the word authenticity because it is so dangerous," Mr. Harnoncourt said. " 'Museum music' does not interest me. I have no intention of organizing guided tours to visit Louis XIV or Johann Sebastian Bach."

He later expanded his repertoire to include 19th-century opera favorites such as Verdi's Aida. His individually accented interpretations, including composers as diverse as Beethoven and Richard Strauss already led Switzerland's Neue Zuercher Zeitung newspaper in 1999 to call him "the protagonist of the new expressionism."

His 2001 Grammy Award for a recording of Bach's St. Matthew Passion was only one of dozens of honors reflecting his musical standing.

Mr. Harnoncourt believed art was the foil to modern society's materialism, which he saw as a threat to Europe's cultural values. As a boy, he acquired his knowledge of sacral music at the cathedral in his home city of Graz, Austria.

"We as musicians - indeed all artists - have to administer a powerful, a holy language," Mr. Harnoncourt said in a speech for the Mozart Year of 1991, two centuries after the Austrian wunderkind's death. "We have to do everything in our power to keep it from getting lost in the maelstrom of materialism."

Mr. Harnoncourt was born in Berlin on Dec. 6, 1929. His father, Eberhard, belonged to the house of the Count de la Fontaine und d'Harnoncourt-Unverzagt of Luxembourg-Lorraine, and his mother, Duchess Meran and Baroness of Brandhofen, was a great-grandchild of Archduke Johann of Styria.

He was a cousin of the late Anne d'Harnoncourt, director of the Philadelphia Museum of Art.