It was the mid-1990s, and Mariinsky Ballet virtuoso Sergei Vikharev was perplexed. Post-glasnost, he was now dancing the ballets of once demonized defectors Michel Fokine and George Balanchine—set by licensed repetiteurs from inviolate “texts.” But who was protecting his own theater’s classics—Swan Lake, La Bayadère, The Sleeping Beauty? Where were their “texts”?

They existed, he found out, in faraway Harvard. After the 1917 Russian Revolution, Mariinsky chief repetiteur Nikolai Sergeyev had fled to the West with 33 cartons of notated ballets. By torturous chance, the cartons landed at a Harvard University library. Vikharev got copies. He taught himself the complicated Stepanov notation, starting with the consummate 1890 Tchaikovsky-Petipa classic, The Sleeping Beauty. A team of Russian colleagues scoured museums for images of the old décor and costumes.