Gerard Mortier, who has died aged 70, was one of the opera world's highest flyers, a fearlessly didactic festival director who was also a guru of opera houses and of what they should be doing, or not doing.
In these respects he was a true revolutionary who, in Brussels, Salzburg, Paris and finally Madrid, was famously progressive in his enthusiasm for modern works and how to incorporate them in a general operatic repertoire.
Inevitably, being both combative and the product of a Jesuit boarding school education, he encountered (indeed encouraged) opposition as well as success. Born a baker's son in Ghent, he worked out his operatic philosophy while running the historic but conventional Theatre de la Monnaie in Brussels, imprinting on it his style of cerebral showmanship.
An opponent of the star system, he declared that the corridors of the Brussels theatre were too narrow for Pavarotti. As a child, running his own domestic puppet theatre, he had got to know what he wanted and he spent the rest of his life achieving it around the world. Only New York failed him.
The Salzburg Festival was his first big international target. Although, as Herbert von Karajan's successor in 1990, he was neither a conductor nor an opera director, he ruthlessly set about clearing the Augean stables - as he called them - of empty extravagance of the sort that Karajan had left behind.
Not only did he change the Salzburg approach to Mozart, which took him ten years to do, but he crowned his tumultuous Salzburg decade with a presentation of Johann Strauss's Die Fledermaus that was seen as an attack on both the festival and the increasingly right-wing Austrian government.
By then he had already recruited the sensational Peter Sellars as one of his opera directors with productions of Ligeti's Grand Macabre and Messiaen's St Francis of Assisi.
With the arrival of the 21st century, his next target was Paris. As assistant to the outgoing supremo Rolf Liebermann, who had already set in motion a process of modernisation, he promptly staged Schoenberg's Moses and Aron, then proceeded in the way he had begun with Wagner's Tristan and Isolde in Peter Sellars's masterly video-based staging.
By 2007, New York had begun to woo him. Though he would like to have been given the Metropolitan, the failing New York City Opera was what he was offered. But the cost of his plans for updating the theatre and adjusting the repertoire - Mortier did not come cheap - caused panic. When offered a budget of $36m for his first season, he replied that he could not run a company that was scarcely richer than the smallest company in France.
Though by this time he reputedly had his eye on Bayreuth, it was the Teatro Real in Madrid that won him for the final portion of his career. Productions of works by Janacek and Philip Glass, culminating two months ago in Charles Wuorinen's Brokeback Mountain - "less sentimental," Mortier claimed, "than the film" - brought the Spanish company up to speed.
But by then Mortier's days were numbered. Since September 2013 he had been suffering from pancreatic cancer, a more merciless opponent than any opera company, and he died in his native Brussels last week. He is survived by his sister Rita.