Unlike the master works of painters, poets, playwrights, and composers, a choreographer’s creation gains permanence only by entering the permanent repertory of a dance company committed to presenting it to audiences. Yes, there are video documentations of great dances, sometimes reclaimed from the dusty archives of a studio or an administrative vault. But these often grainy images, flattened in the medium of the screen, are a pale semblance of the flesh-and-blood physicality of movement and form that originally made the dance great.