In the fall of 2017, Michael Tilson Thomas announced that he would step down as music director of the San Francisco Symphony in 2020, ending a quarter-century run that has been as transformative as any conductor-orchestra partnership in recent memory. Under Thomas’s leadership, the orchestra reshaped 20th-century symphonic repertoire, restoring American music to its rightful place in that constellation and emphasizing the role of its “mavericks,” who included John Cage, Carl Ruggles, and Lou Harrison. And the agility with which it embraced 21st-century innovations, such as multimedia and its own recording label, left many orchestras playing catch-up. Talk of the “Big Five” American orchestras — Boston, New York, Chicago, Cleveland, and Philadelphia — suddenly seemed antiquated.
So it would be natural to regard Thomas’s final Boston performance as the Symphony’s music director on March 24 — with a program of Mendelssohn, Beethoven, and his own “Agnegram” as a curtain-raiser — as part of a well-earned victory lap. But his curiosity and drive to tackle new projects remains undimmed, to judge from a lengthy recent interview. Indeed, it was precisely his feeling that there was still so much else to do that prompted the decision to step aside from the role. (He will be succeeded by Esa-Pekka Salonen.)
“It was a question of realizing where I am in my life,” Thomas said by phone from his house in Marin County, north of San Francisco, which he shares with his husband and manager, Joshua Robison. “So much of my life I have been the youngest person on stage. Now I’m almost always the oldest person onstage.
“But I still think of myself as the youngest person onstage, in terms of where my spirit and my curiosity are,” he continued. “I have a list of projects which are what I would call the things I definitely want to have done before I’m out of here.” Chief among them, he said, are composing and writing.
He will not want for opportunities as far as conducting is concerned. Thomas will maintain his relationships with two other orchestras with whom he has longstanding ties: the London Symphony Orchestra, where he is conductor laureate and approaching the 50th anniversary of his first appearance; and the New World Symphony, the pioneering youth orchestra he founded in 1987.
He will also continue regular work with the San Francisco Symphony as music director laureate, chiding an interviewer who mistakenly referred to his future title as emeritus, with its connotations of retirement.
“I’m not emeritus,’’ he said, laughing. “I’m laureate! Which means I’m still doing a lot of things. If I were emeritus, I’d maybe be creaking in there once a year, waving at people.”
Asked how today’s San Francisco Symphony differs from the one he took over in 1995, Thomas called it “a much more virtuoso, sophisticated, adventurous orchestra. The personality of the orchestra is one that enjoys exploring new, alternative solutions to musical questions.” The kernel of that spirit extends back to his early guest conducting engagements, when, leading Sibelius’s Sixth Symphony, he noticed that the San Francisco was “willing to go much further [than other orchestras] in the direction I wanted to go” in introducing a “folkloric” element into the orchestral playing. And it persists today, as he described his approach to Beethoven’s “Eroica” Symphony (on the Boston program), which
he now strives to give a more intimate and less monumental profile than it usually assumes. This has involved having some instruments adopt a softer, more nostalgic tone, and reducing the number of strings playing in certain passages.
“There are orchestras in some places that . . . it’s just in their comfort zones to always do something a particular way,” he explained. “And they might be less than comfortable with, ‘Oh, here it’s something different going on.’ But in San Francisco, I’ve been lucky to find colleagues who say, ‘Sure, let’s try it. Does it feel more comfortable? Can we do something creative and interesting with this?’
“I’ve been here 25 years,” he said, “and my relationship with the orchestra, the kinds of things we talk about, is at its height, I feel. I’m so appreciative of that.”
Though composition has played a lesser role in his career than conducting, he has a number of projects on which he plans to work. He mentioned a spate of recent performances of his 2016 work “Four Preludes on Playthings of the Wind,” a setting for chamber orchestra, “bar band,” and voices of a 1920 Carl Sandburg poem. The poem is a critique of imperial ambitions and of a blind adherence to the idea of one’s country as “the greatest nation/nothing like us ever was,” as Sandburg writes.
“This is a direction that a lot of my music coming up these next few years has,” Thomas said. “Political and social topics, and my concern that we all have a chance to remember, as I put it at Tanglewood last summer, those truths which were formerly held to be self-evident.”
When asked whether he thinks those truths have become less self-evident over the past few years, his answer was compact: “I would say so, yes.”
Even that seriousness, though, cannot mask for long Thomas’s curiosity, the joy in the next discovery or the next piece to be reinvestigated. That kind of inquisitiveness animates all of his artistic projects, and is likely to be his chief legacy in San Francisco.
“I so believe, as I always have, that this music we make is a very serious and important cultural testimony,” he said. “But the approach to it, lifelong, is something that needs to be full of lightheartedness and questioning and a kind of delight and wonder in the many things that it could be.”
An earlier version of this story incorrectly stated when Michael Tilson Thomas made the announcement that he would leave his post as music director of the San Francisco Symphony.
SAN FRANCISCO SYMPHONY
Presented by Celebrity Series of Boston. At Symphony Hall, March 24, 5 p.m. Tickets $77-$135. 617-482-6661, www.celebrityseries.org.David Weininger can be reached at firstname.lastname@example.org. Follow him on Twitter @davidgweininger.