Merce Cunningham was one of the three most influential choreographers of the 20th century. (The other two were George Balanchine and Martha Graham.) He choreographed nearly 200 works of modern dance between 1944 and his death, in 2009, fundamentally redefining the genre of modern dance for the second half of the century. This year marks the centennial of his birth, and classic Cunningham dances are being performed all over the world. One performance stands out: the double bill of Beach Birds and Biped at the Kennedy Center, in Washington, D.C., which will run from October 3 to 5.

Beach Birds is indisputably classic Cunningham, but Biped belongs in a celestial category all its own. I’ve come to regard it as Cunningham’s last masterwork and, given its premiere in 1999, the last great work of modern dance created in the 20th century. It’s also the most luminous example of Cunningham’s career-long fascination with the intersection of dance and advanced technologies. Not only was Biped choreographed on a computer, but onstage the living bodies of the dancers are often juxtaposed with ghostly, “motion captured” images of their virtual selves.

From the vantage point of 2019, it’s clear that Biped’s shiny digital surface was only part of the story. The deeper, more lasting legacy is suggested by its two-syllable title: Biped is a mission statement in which Cunningham acknowledges the foundational role that verticality—upright “bipedal” posture—has always played in his choreography. This embrace of verticality is one of the characteristics that most clearly distinguishes Cunningham from his early mentor Martha Graham, whose style dominated American modern dance during the first half of the 20th century.

Beach Birds is classic Cunningham, but Biped belongs in a celestial category all its own.

Cunningham once said, “I start from a standing position because that’s mostly the way we move.” By contrast, a Graham class almost always begins with the dancers seated on the studio floor. Why were pre-Cunningham modern dancers so determined to reject uprightness? In a word, ballet—the art form they defined themselves in opposition to. Verticality was central to classical dance, which was animated by the desire to defy gravity, to be liberated from the earth. Cunningham was the first modern-dance choreographer to embrace, rather than reject, this vertical aspiration. His “rapprochement” with many of the conventions of classical dance helped radically redefine our conception of modern dance.

On yet another level, Biped is also one of the most personal dances Cunningham ever choreographed. Here’s why: By the late 1980s, severe arthritis had made it increasingly difficult for Cunningham to maintain an upright posture for any extended period of time; and by the mid-90s he realized he was no longer able to choreograph from the bipedal stance that had been his starting point since 1944, when he parted ways with Graham. In order to create Biped, Cunningham had to solve the greatest practical challenge of his career: how, at the age of 80, to preserve his upright orientation. He found the answer in the ergonomics of the straight-backed chair, “pulled up” to the desk on which the screen of his computer was stationed. Kinesthetically, the act of sitting in such a chair has more in common with standing at the ballet barre than with reclining on the floor. This was Cunningham’s personal—and characteristically modern—solution to the ancient riddle of the Sphinx. —Roger Copeland