"Remember," said her godmother, "you must leave the ball before the clock strikes twelve. If you do not, your coach will again become a pumpkin, your horses will become mice, your coachman will turn into a rat, and your footmen into lizards, while you will find yourself once more in shabby clothes."
All the evening, the prince kept at Cinderella's side, dancing with her and serving her dishes at suppertime. Indeed, his mind was so taken up with her that he forgot to eat a morsel himself. While Cinderella was talking to her stepsisters, the clock chimed a quarter before twelve.
She thought it not yet eleven when the clock struck twelve. She started then in fright and fled from the ballroom swiftly before anyone saw the rags her raiment had become. The prince ran after her, but he did not catch her. All he could find of her was a little glass slipper lying upon this staircase.
Thus it was as the clock struck midnight and the bells filled the air. It became as if the night had never been, as if no ball had ever happened. The flowing gown that Cinderella once wore was again a humble slip, and the ringing in of the midnight hour carried Cinderella far away with tears in her eyes, as the prince was left pondering over the sparkling slipper left on the staircase.
-From The Little Glass Slipper