Essex (Leonardo's Swans) chronicles the convoluted fate of the Elgin Marbles -- and their journey from the Parthenon to the British Museum -- through the stories of two powerful women: Mary Nisbet, wife of the Earl of Elgin, the British ambassador to Constantinople; and Aspasia, mistress of Pericles, renowned statesman, general and orator in in classical Athens.  (GRE385, $15.00)