Once upon a time, so the story goes (you may read it for yourself in the dear old tales of Hans Christian Andersen), there was a prince who disguised himself as a swineherd. It was to gain admittance to a beautiful princess that he thus came in disguise to her father's palace, and to attract her attention he made a magic caldron, hung around with strings of silver bells. Whenever the water in the caldron boiled and bubbled, the bells rang a little tune to remind her of him.