Every generation discovers Diaghilev’s Ballets Russes anew. From 1909 to 1929, this crucible of creativity—with roots in the imperial theaters of Russia and a reach into the realms of neoclassicism and modernism—brought together music, design, choreography, and costume in one astonishing ballet after another. The impresario Sergei Diaghilev led the way with his clarion call, “Étonne-moi!” (Astonish me!) And so they did. Who are they? Stravinsky. Prokofiev. Bakst. Benois. Golovin. Goncharova. Fokine. Nijinsky and his sister, Nijinska. Massine. Balanchine. This exhibition at the Morgan, drawn from the Robert Owen Lehman collection, includes scores, sketches, drafts, and other work tools used to reinvent not just classical dance but theater in the 20th century. —Laura Jacobs