In 1963, de Mille sent a sealed envelope to her union, the Stage Directors and Choreographers Society, with a handwritten note saying not to open it because it had the “eminently stealable” idea and outline for a play, and, at the time, she couldn’t copyright it. SDC decided to celebrate its 60th anniversary by calling for submissions guessing what was in that envelope, and a panel chose five of the submitters to make short dances based on their guesses. – Dance Magazine