Those dueling Greek painters return in a new guise, as Mario Merz, in the Zeuxis role, covers a glass table with an array of fresh vegetables and fruit, changed daily by a New York caterer ( Spiral Table , 1982), while Christo, playing Parrhasios, conceals the familiar Cezannesque shapes--wine bottle, vase, etc.--under a drapery of canvas ( Package on a Table , 1961).