The ascendancy of the Los Angeles Philharmonic is the salient event in American orchestral life of the past twenty-five years. In 1992, the L.A. Phil was on no one’s list of leading ensembles; the classical-music business had it pegged as a second-tier orchestra that could never quite escape the shadow of Hollywood. In that year, though, the young Finnish composer-conductor Esa-Pekka Salonen took over as music director, and New York-based critics increasingly found themselves booking flights west. The orchestra had already made advances under the guidance of Ernest Fleischmann, its longtime executive. A new-music series was gaining momentum; programming had diversified; Frank Gehry had drawn up plans for a futuristic concert hall. Salonen, cerebral and stylish, brought those ideas to fruition, and added many of his own. He was met with skepticism early on, as I recounted in a 2007 Profile, and yet by the time he left, in 2009, the L.A. Phil was widely regarded as not only the liveliest of American orchestras but also the most robust. When Disney Hall finally opened, in 2003, it created a psychological space in which living composers no longer came across as intruders. The orchestra presented more contemporary music than any ensemble of its size, and, at the same time, it achieved financial stability, disproving the notion that new music was box-office poison.

Deborah Borda, who has been the L.A. Phil’s president and C.E.O. since 2000, played a decisive role in its rise. Managers tend to fall into two categories: those who prize order, thereby risking an excess of caution, and those who foment creativity, thereby risking chaos and waste. Borda has the rare ability to cultivate experiments and impose discipline in equal measure. The music world, by no means crowded with leaders of this calibre, has long wondered what she might do next. She seemed likely to assume an even more expansive role, such as running Lincoln Center or Juilliard. Instead, last week, she caused a bicoastal tizzy by announcing that she would return to the New York Philharmonic, which she had led before going to Los Angeles. Back in 2000, her move west had looked like a step down. Now, in a spatial paradox worthy of M. C. Escher, her move back east seems a step down again—not least because of her own institution-building powers. (L.A’s budget is a hundred and twenty million dollars; New York’s is seventy-five million.) Yet the choice is not as strange as it appears. Borda relishes challenges, and New York will give her plenty of them—notably, the task of finding hundreds of millions of dollars for the renovation of David Geffen Hall.

Most of the commentary on this unexpected development—including Anthony Tommasini’s, in the Times, and Russell Platt’s, here at The New Yorker—has focussed on its implications for the Philharmonic. What it portends, no doubt, is rapid-fire change in every sector of the organization. Just as important, however, is the question of what lies ahead for the mighty L.A. Phil. By all accounts, Borda’s decision to leave was abrupt, and the transition to a new regime may not be as seamless as the one she oversaw in 2009, when Salonen handed the reins to Gustavo Dudamel.

What the L.A. Phil needs is continuity, not change. The orchestra was already a singular, potent institution when Borda arrived: her contribution was to understand its nature and move it forward. The vision of Fleischmann—a tough, brilliant administrator who was born in Germany in 1924, and immigrated with his family to South Africa three years after Hitler took power—remains at the heart of the L.A. Phil project. Back in the nineteen-sixties, he imagined a new kind of orchestra that, instead of endlessly recycling Romantic repertory, would become a flexible community of musicians traversing the centuries. I first met him in 1994, and what I remember best about the interview was the terrifying car ride to the restaurant where we had lunch. Driving his Audi while gesticulating emphatically with both hands, he struck me as a bit of an Ahab-like madman, and therefore the right person to revolutionize the hidebound American orchestra.

Fleischmann’s ideas intersected with peculiarities of Southern California culture. The L.A. Phil had been a little weird from the start; its founder, William Andrews Clark, Jr., the errant scion of a ruthless Montana copper king, also assembled a matchless collection of Oscar Wilde memorabilia. The migration to Los Angeles of many of Europe’s leading composers and musicians, chief among them Schoenberg and Stravinsky, inevitably shaped the orchestra’s identity, even if it was slow to recognize their work. (Schoenberg’s heirs still feel that the L.A. Phil has not done him justice.) When Fleischmann and Salonen finally began to shift the repertory toward the present, they could build on a small but spirited group of new-music-loving patrons and donors, who had supported pioneering ventures like Evenings on the Roof, which in time became Monday Evening Concerts. That culture of progressive patronage is, as I pointed out in a column last fall, crucial to the dynamism of Los Angeles music. By the end of the Salonen era, the new-music series, Green Umbrella, was drawing crowds of well over a thousand people, causing visiting composers to do double-takes when they walked onstage.

The orchestra I observed in 2007 was vibrant, but it still fell short of its stated ideals. A select company of compositional celebrities, the likes of John Adams, Thomas Adès, and Steve Reich, held their own against the dead, yet many others felt overlooked. Happily, the L.A. Phil’s conception of new music has kept broadening in recent seasons. At Green Umbrella shows, you are as likely to encounter the molten avant-gardism of Chaya Czernowin or the desert-tinged soundscapes of Andrew McIntosh as you are an audience-friendly post-minimalist. Intelligent pop collaborators are also part of the mix, as the upcoming Reykjavík Festival attests: the Icelandic bands Sigur Rós and Múm are joining in, and Björk will make a rare orchestral appearance. Such voracious programming reflects the taste of Chad Smith, who has handled artistic planning since 2006, and who last year became the chief operating officer. Increasingly integral to the L.A. Phil’s mission, Smith has forged collaborations with filmmakers, choreographers, architects, visual artists, and educators, enmeshing the orchestra in Los Angeles culture.

The L.A. Phil’s 2017–18 season, just announced, is so far ahead of that of any rival, in America or around the world, that the orchestra is mainly competing with itself. Close to half of the featured composers are contemporary. The gifted young director Yuval Sharon, who in 2015 unleashed the astonishment of “Hopscotch,” will stage Annie Gosfield’s adaptation of “The War of the Worlds,” with sonic eruptions from locations across Los Angeles. The Chilean company Teatrocinema will offer a virtual-reality reimagining of “Das Lied von der Erde.” White males are less dominant there than they are elsewhere; four female conductors lead programs during the season, at a time when many ensembles can muster none. Outside the hall, the orchestra administers YOLA (Youth Orchestra Los Angeles), which provides instruction to some eight hundred students, most of them Latino or African-American. Ninety per cent of its 2016 class went on to college.

The most venerable American orchestras take pride in having a distinctive sound: the Philadelphia strings, the Chicago brass, the Cleveland blend. The New York Philharmonic has prized a virtuosity that edges, for better or worse, into brashness. The L.A. Phil, by contrast, has a tradition of no tradition: its sense of self resides not in a fixed repertory but in a mediation between past and present. That spirit of flux has persisted across several generations and now seems part of the institution’s identity—although, in the fragile sphere of the performing arts, nothing can be considered permanent. As a critic, I have made a habit of following this orchestra wherever it goes, and I am therefore hesitant to offer advice as it plots its future. But the adage of another noted Southern California composer comes to mind: keep on keeping on.