''I never even thought of collaborating with another choreographer," says Ellen Highstein, director of the Tanglewood Music Center in the Berkshires.
She's talking about Mark Morris, who is creating a new dance this month at the center. Called ''Cargo," it's set to Darius Milhaud's ''La Creation du Monde." The Mark Morris Dance Group and the musicians of the TMC will premiere the piece at Tanglewood June 26 and 27. It's Morris's first TMC commission.
But this is actually Morris's third season in residence at the center, where around 150 young composers, singers, instrumentalists, and conductors gather each summer to hone their crafts in the inspiring surroundings of the Boston Symphony Orchestra's summer home.
''That fact that [Morris] works in dance is almost irrelevant," Highstein says. ''It's the fact that he's a great musician that counts." Morris choreographs with the score in hand, and his rehearsals sometimes end with his dancers gathered around the piano for a song fest. Morris treats dancers' bodies as musical instruments.
Hence his approach to working with the TMC fellows and his own dancers. ''The musicians will learn some of the movement phrases, and the dancers will learn the singing and percussion," Morris says of the jazz-inflected Milhaud piece. The paying public won't see the role switching, of course -- nor did anyone outside the Tanglewood family witness the music fellows dancing a section of Morris's ''Falling Downstairs" two years ago, when its Bach score was played live by none other than Yo-Yo Ma.
The idea is that by the time the public does see the finished product in performance, there will be a special synergy between dancers and musicians. In the case of the Bach, Highstein says, ''just knowing how it felt to do those steps made a huge difference in the musicians' perspectives."
Morris is famously insistent on performing with live music rather than canned. And in the early stages of rehearsing a new work, when he can't have musicians in the studio, he'll use several different recordings so the dancers don't get attached to a particular tempo or interpretation before they work with the musicians who will ultimately accompany them.
In addition to ''Cargo," the Tanglewood program will include three earlier Morris dances, which show the range of the choreographer's musical taste. ''Somebody's Coming to See Me Tonight" is set to Stephen Foster songs. The score for ''Mosaic and United" consists of the eponymous string quartets by Henry Cowell, a 20th-century composer whose interest in the music of Indonesia and India parallels Morris's own fascination with those countries' cultures. And ''Lucky Charms" is set to the frothy ''Divertissement" of an earlier 20th-century composer, Jacques Ibert.
''Cargo" will be performed only twice at Tanglewood, but it will be part of a Morris tour later this year, as well as the company's 25th-anniversary celebrations next season. And when the Mark Morris Dance Group moves over to the Jacob's Pillow Dance Festival after the Tanglewood gig, some of the fellows will follow to accompany the Morris program there.
While they're all still at Tanglewood, though, Morris will stage a square dance for the dancers and musicians, again away from the public gaze.
''There's nothing like having performers look each other in the face," Morris says. ''Dancers are bad at social activities, and musicians are bad at walking on the beat. So this is going to be like a special-ed kind of thing."
Tanglewood, June 26-27. 888-266-1200; www.bso.org.