Choreographers, dancers, and artistic directors regard the historic repertory with wariness if not distaste. Yesterday's creative achievements may be celebrated and mythologized. But unlike classical music or opera, the dance field grants its past only a small slice of the active repertory. Ballet companies stake their reputations on a few periodically renovated nineteenth-century staples and skim over their twentieth-century holdings. Modern dance companies, usually powered by the work and continuing productivity of a single choreographer, have attics full of discussed material. Often it seems the only reason to undertake a revival is to compensate for a scarcity of new creations. Here, Siegel talks about dance companies mining their heritage.