Take, for example, the Philadelphia man who, in1989, made a historic discovery in a flea market. The man, whose identity was never made known, bought an old painting at the flea market for $4. He did not like the painting, but bought it because he liked the frame. When he got the painting home and took it out of the frame, he was surprised to discover a folded-up document wedged between the painting and the backing of the frame