Matthias Pintscher speaks about Boulez’s “Dérive 2,” which the composer’s old ensemble performs in New York this weekend.Pierre Boulez, one of the most commanding musicians of the past century, must have been asked countless times, before his death in 2016, what he thought his legacy might be.It was a mark of his stature that he had so much to choose from. Perhaps his work as a conductor, one of rare clarifying power? Perhaps his visionary inspiration as an institution builder, in his native France and elsewhere? Perhaps his polemical writings? But when pushed, he would often point to his formidable, intricately constructed compositions.“Performances are transient, you know,” Boulez said in an interview in 1999. “That’s just something which happened, and you are happy sometimes. But, I mean, that’s not the main fact in my life. I would like that my works survive myself, that’s all.”Will they? And with what impact?Boulez can no longer promote them himself after all, and some of his most illustrious champions — Daniel Barenboim, Maurizio Pollini — are sadly starting to pass from the stage. Yet there are still artists tending the Boulezian flame, chief among them the Ensemble Intercontemporain, the Parisian new-music group that Boulez founded in 1976, and its music director, the composer-conductor Matthias Pintscher. Together, they will perform one of Boulez’s late, monumental works, the 45-minute, 11-instrumentalist “Dérive 2,” at Zankel Hall on Saturday. It will be just the third time that a Boulez piece has been performed at Carnegie Hall since his death.Pintscher, 52, first met Boulez in the late 1990s, and they later became close friends. Describing his mentor as “the most curious, alert, giving and generous man,” Pintscher spoke in a recent phone interview about interpreting Boulez’s works and how best to think about their influence. Here are edited excerpts from the conversation.Boulez conducted an earlier version of “Dérive 2” at Carnegie Hall 20 years ago this week, but this is still music that many listeners — even new-music devotees — struggle to get to grips with. How would you describe it?You are absolutely right, because “Dérive 2” is maybe one of the most austere of the big, major works, in comparison with “Répons,” or “Sur Incises” in particular. I think it’s an absolutely significant score in terms of how it’s put together, the architecture, and his idea of constantly building and extending and letting music just grow by itself. You know, like you plant a seed and just watch how it goes, and a twig becomes a branch, and becomes a tree, and the tree then stands very, very solid.The time has come to revisit the text with all these Boulez scores, especially with the Ensemble, where we still have members that have played this piece with Pierre. There’s always like, yeah, but Pierre did that slightly faster or slower, or he waited there, and it’s interesting because — I mean, we’re talking about very subtle differences — the scores tell something different, and I find it absolutely fascinating to now not be a copy of Boulez, but to really get back to the text.It’s quite funny that Boulez, who as a conductor had such a reputation for fidelity to text, may not have been entirely faithful to his own scores.I mean, it’s like what people always ask myself also, “Do you love playing your works? Doesn’t it feel good, or what does it do to you?” I personally interpret my own works exactly in the same way as a Bruckner symphony, or a Schubert symphony, or a piece by Boulez. When I’m asked to perform a work of myself that goes way back, more than a handful of years or even more than 10 years, I really have to sit down and learn the score. With Pierre it was the same.Of course we had conversations about “Dérive 2.” He was making jokes like: Woah, tonight “Dérive 2,” oof, buckle up, roll up your sleeves. He said this in his most charming and witty way. But yes, it’s a big piece, it’s a long piece, it is very demanding, it is very challenging. It’s like Ravel: Everything is wonderfully logical, but once you abandon that and you forget about the structure and how it has been built, you can really immerse yourself in the energy and the flow of that music.You conduct a huge amount of new music. Does Boulez — and more broadly the Darmstadt School-era composers like Nono and Stockhausen, who shot to prominence in the 1950s — still have a definable influence on composition today, especially on young composers?That’s a big question, huh? I think we have to understand that the significance, the legacy of a composer cannot be measured by the statistics of how many performances a composer or a certain piece has at a certain time. It’s like those works are landmarks for their time — as is the “Goldberg” Variations. I don’t know how many times the “Goldberg” Variations are being performed worldwide, daily.It’s a reference. It adds to the roots of music history, as we understand that the very late Brahms becomes the early Schoenberg, the very late Schubert becomes the very early Bruckner, and the very late Stravinsky becomes Pierre Boulez. If you look at “Threni,” for example, by Stravinsky, there is some sort of transition to where Boulez picks it up, and I think those links in music history are fascinating and important.He created these monuments; they’re cathedrals. “Répons” is an absolute masterwork. It’s very hard to program because it requires an ideal space, very heavy electronics and it’s extremely difficult to play. It’s not just a piece that you put on. So I think we have to understand that it can’t be measured by how many times a piece is being performed. The material that we had in Paris last week was material No. 61. There’s 61 sets — probably more! — of “Dérive 2.” That tells us something.Might we say that this is a transitional period, and it’s too early still to tell — that Boulez’s compositional legacy is still unclear, even if his significance is obvious?I can’t really tell. Maybe you’re right and it’s too early. But as I said, I think those scores are manifests and documents of a certain time, a time of change.There’s so much talent out there. I’m teaching at Juilliard, and those young artists, yes, they’re really troubled by the question, “How can I find my voice?” And in terms of finding your own basic voice, it’s a basic requirement to study the “Brandenburg” Concertos, to study “L’Orfeo” by Monteverdi, to look at the G major Schubert Sonata, look at Schoenberg — and look at Boulez. Like it or not, it is a reference, it is a major key holder in music history. I personally find the music mesmerizing, I find it beautiful, but maybe because I’ve lived for it so long.They’re demanding because you have to use the ear, you cannot just beat what you see and think that does justice to the piece. It requires the human experience, and maybe now that I’m 52, I only start to really realize what it means to play his works with the space that they need — with all the respect that I have for what I see in the text, it also needs to be translated into a human reality.And that’s why those works are major, and that’s why they’re like a Beethoven symphony, or that Schubert G major piano sonata, because it needs you. It needs the individual, the human to find the right context for it. You cannot just play them through, and think that’s it. There’s more; there’s layers. More