One thing that students of dance history are often unable to study is choreography itself. Although research can reveal much about the music, decor, and dramatic significance of a choreographic work, the evanescence of dance may make it impossible for us to know how that work lived and moved upon a stage. Therefore the Royal Danish Ballet's Bournonville Centenary Festival in Copenhagen (November 24-30, 1979) was one of the most important dance events of recent years. Honoring the great Danish choreographer August Bournonville, who died in 1879, it offered, on the Old Stage of the Royal Theatre, nine works that are considered authentically Bournonville in their choreography. Except for the William Tell Variations and a few miscellaneous bits and pieces (for instance, such trifles as the Polka Militaire and the Jockey Dance, presented in America by the touring ensemble of Royal Danish Ballet soloists), that is just about all the Bournonville that has survived, and one of those nine items is merely a pas de deux. But Bournonville choreographed more than fifty works, and so one can only wonder what treasures have been lost. However, since we have no ballets at all by Noverre or Vigano, and since Giselle, our sole surviving ballet by Perrot, is a collaboration with another choreographer, we should feel lucky to possess nine works. Come to think of it, how many more ballets have survived by Petipa? And, surely, only a few more ballets by Fokine are now revivable-even though Fokine was a choreographer of our own century. Boumonville's nine ballets are therefore quite a lot. As most dance lovers know, they survived simply because Denmark in the late nineteenth and early twentieth century was isolated