The conductor Esa-Pekka Salonen and the pianist Igor Levit discuss Ferruccio Busoni’s Piano Concerto, a rarity they are performing in San Francisco.There are piano concertos, and then there is Ferruccio Busoni’s Piano Concerto.Completed and premiered in 1904 by the Berlin Philharmonic with the composer, a virtuoso of Lisztian ability, at the piano, the piece retains a near mystical reputation. It is so difficult that only the most commanding of pianists dare take on its 75 minutes and five movements. In the last and oddest of them, a male chorus implores listeners to draw close to Allah, singing from the text of an early 19th-century version of “Aladdin” by the Danish playwright Adam Oehlenschläger.If the concerto is performed more often than it used to be, it is still enough of an anomaly in the repertoire that performances are a significant event, one of which is its San Francisco Symphony premiere this week, with the conductor Esa-Pekka Salonen and the pianist Igor Levit, joined by the men of the San Francisco Symphony Chorus.In a joint interview, Salonen and Levit spoke about the concerto and Busoni’s confounding stature today. Here are edited excerpts from the conversation.Levit said that the Busoni concerto is so difficult, it can “widen your curse words repertoire.”Ian C. Bates for The New York TimesMy first question is, why?ESA-PEKKA SALONEN May I propose a counter-question? Why not? Last time we performed together, which was many years ago, we had a little chat over dinner about what to do next. We both happen to love the Busoni, and we thought, OK, let’s do it. These are decisions that are easily made over dinner, and then when you get to it, you realize what you’ve done. Still, I’m very happy, and the more I study the piece the more I like it, which is actually a very good sign, because it’s not always like that. Some of the ideas, especially harmonic ideas, are incredible.I can’t make up my mind whether it is a parody, or deadly serious, or what.IGOR LEVIT I think it’s both. It’s highly celebratory. I mean, the roof flies off the building, right? In the “All’Italiana,” it’s very satirical. It’s incredibly beautiful, it’s funny, it’s solemn. It has it all.Busoni has always been one of those role models I never met, in a way like an idol figure, regarding the way he thought and especially wrote about music, his utopian idea about what free music actually is, his idea about what the creator’s job is, which is to set up your own rules and not follow the rules of others.As a composer, as a pianist, as a thinker, teacher, we are speaking here of one of the most incredible minds of at least the 20th century. He was this larger-than-life figure, and I think it’s a larger-than-life piano concerto.We hardly ever hear Busoni’s music now, and yet he was so significant historically.SALONEN He really was a trailblazer, and he predicted lots of things that are now commonplace in contemporary music, like microtonality. He even at some point was fantasizing about computers, before the concept even existed.As a Finnish musician, I must say that we are very grateful to him, because he spent a couple of years in Helsinki. He was a very, very strange bird in Helsinki cultural life. And he was an incredibly important influence to Sibelius, because Sibelius suffered from this kind of country boy complex compared to contemporaries like Richard Strauss.Busoni and Sibelius became really good friends. I’m absolutely sure that to have somebody like that as a conversation partner and drinking buddy — they did quite a bit of that apparently — was incredibly important. They even had a little club, a group of friends who called themselves Leskovites, because Busoni’s dog was called Lesko. There’s a bar in Helsinki where they hung out and developed the new music for the next century.LEVIT One of the most important teachers I had in my life was Matti Raekallio. Matti is from Helsinki. Matti’s thesis was on Busoni’s fingering. He introduced me to the concerto when I was 19. He introduced me to the “Fantasia Contrappuntistica.” He introduced me to the way Busoni would play the piano, which is a very positional kind of playing, and not a graphic kind of playing.For, let’s say, a normal piano player, who grew up with rules and who studied in Central Europe or wherever, there is no such thing as Ferruccio Busoni, all you know is Bach-Busoni. You might know two or three of his chorale preludes. That’s it. But you don’t get in touch with the actual man. It was Matti who opened this incredible door for me into the thinking of the man and to the music. So even I know Busoni through Finland.SALONEN It’s funny: The first time I ever heard anything by Busoni was when I was a composition student in Siena, Italy, with Donatoni back in the late ’70s. There was a concert when some Italian pianist played Busoni’s arrangement of Schoenberg’s Opus 11, three piano pieces. He arranged Schoenberg’s piano pieces for the piano. And I thought that was the silliest thing I’d ever heard in my life.Igor, is the concerto as hard as everyone says it is?LEVIT Yeah, this is a piece to widen your curse words repertoire.What are the hardest things in it?LEVIT There are moments in the second movement that, I mean, they’re just beyond what should be acceptable in terms of how much you have to work to achieve a certain result. Toward the end, there’s this rather long passage with incredibly difficult jumps, which are asymmetrical between the left hand and the right hand. This alone is kind of utopian, and it’s also written such that no one in the audience will actually hear what you’re doing, because the orchestra is so massive.The cadenza and conclusion of the ‘All’Italiana’John Ogdon, piano; Royal Philharmonic Orchestra; Daniell Revenaugh, conductor (Warner)There is a spot in the “All’Italiana,” right after the cadenza, where the piano has these huge chords in left and right and they run toward each other. It’s sort of unachievable, and yet, so what? You constantly are aware of the fact that you as a pianist, are in the middle of playing something extraordinary.Busoni “was this larger-than-life figure,” Levit said, “and I think it’s a larger-than-life piano concerto.”Ian C. Bates for The New York TimesIt doesn’t strike me as an easy piece to conduct, either. The balances, for one thing.SALONEN Well, it’s massive, and as Igor said, there are moments that if you don’t reduce the dynamics and sort it out, the piano will be drowned.LEVIT [Laughing] Please don’t reduce the dynamics and sort it out.SALONEN But there are moments in Brahms’s piano concertos where the piano kind of sinks into the orchestra, and I think part of the expression is that zoom-in, zoom-out thing. It would be very boring if you had 75 minutes of the piano being completely on the surface at every moment. And in this case, the piano has different roles.What is the finale there for?SALONEN I have seen many incomprehensible, weird texts in my life that composers have used, but this one is right up there. I think he was planning to write a music-dramatic work based on the text by this Danish guy. He never got further than setting the final chorus, and then that found its way into the Piano Concerto.The story of this text is so funny, because the playwright was Danish, and he wrote the text in German, but his German was not great. He went and read it out loud to Goethe, and he read it out of the Danish version and translated it into German on the fly. I’m trying to imagine Goethe just sitting there listening to this guy go through this endless play, in bad German. And then various editors went through three or four rounds to fix the grammar, and finally, there is a version that is grammatically acceptable. However, Busoni liked the first version with all the wrong cases and wrong articles.LEVIT Of course he did.SALONEN And there’s something really fabulous about that. It’s basically the boulders in the cave where Aladdin takes the lamp back to. The boulders are very grateful, and they praise Allah for the beauty of nature. And a lot of it is completely incomprehensible.LEVIT But then again we’re speaking about Busoni, who was one of the great internationalists. You’re talking about this universally educated and universally interested guy. So it’s all incomprehensible and odd and weird, and yet not surprising whatsoever.SALONEN So, we’re fans.LEVIT Exactly. More