The magician places two empty packs of gum on the table and between them a third in which a last piece of gum can be heard rattling. He switches the packs around and asks the audience to pick out which pack has the piece of gum. The audience gets it wrong. After several attempts, it is always a different pack from the one they select. The magician finally provides the explanation: ALL THREE PACKS ARE EMPTY. None of them rattle. The packs can immediately be examined! The magician’s hands are visible at all times and can be seen to be empty!