As I walked into the local branch of the public library one afternoon, I immediately noticed a familiar face. Surrounded by six moppets, Aunt Dee was sitting and holding a large and colorful book. I approached, unnoticed, and heard her say. ''Her name was Cinderella, because she liked to sit near the fireplace and watch the cinders.''

''What's a cinder?'' one little girl asked.

''It's a small piece of fire,'' Aunt Dee answered confidently. She went on to tell the classic tale, with certain alterations, showing the illustrations as she went along.

''There was a big party at the palace, and Cinderella and her stepsisters were invited. So Cinderella went to Macy's where a fairy saleswoman helped her pick out a beautiful dress. When it was time to go to the party, the doorman called a taxi for her.

'''Be sure to be home by midnight,' her stepmother warned her. 'I don't like you to be wandering around in the middle of the night.'''

''How would she know it was midnight?'' asked a curlyheaded listener.

''She had a Mickey Mouse watch,'' Aunt Dee said without missing a beat.

''Then what happened?''

''The prince danced with Cinderella all evening, and when he saw what a sweet, kind person she was he fell in love with her. He was so busy loving her that he forgot to ask her for her phone number.

''At midnight, Cinderella remembered her stepmother's warning, and ran out of the palace to where her taxi was waiting. In her hurry she lost one of her lucite shoes. The prince, running after her, found the shoe. 'Only my Cinderella could wear such a tiny, graceful shoe,' he thought. So he sent his staff out to try the shoe on every girl in town. They found Cinderella, and she and the prince were married. She and her stepmother and stepsisters all lived in the palace happily ever after.''

I walked quietly away.

That evening when I called Aunt Dee on the phone I asked her about her stint at the library.

''There was a sign on the bulletin board asking for volunteers to read to children,'' she said. ''So since I have experience reading to children, I volunteered. The children love me.''

''Of course they do,'' I said. ''But why didn't you read the story the way it was written?''

''Oh, come on,'' she said. ''You think I'm going to give those children the idea that a stepmother is a bad person? A lot of them have stepmothers. I myself could have been a stepmother if I had married that fellow who was after me when Uncle Raphael died. That fellow had three children.'' She sighed, whether in regret or in relief I could not tell.

''And telling them about magic nonsense gives them the wrong idea about real life,'' she went on. ''Nobody's going to wave a wand and get them ball dresses, and they had better know it,''

Her point had validity. But I still remembered the fascination of hearing about a fairy godmother who could turn a pumpkin into a coach, and the satisfaction of having Cinderella beat out her ugly, cruel stepsisters. ''Maybe children should know that there are mean people in the world,'' I suggested.

''You think they don't know that anyway?'' said Aunt Dee.