From Aesops's Fables : Brother & Sister

A man had two children, a boy and a girl. The boy was good-looking as the girl was plain. One day as they were playing together in their's mother's room, they came across a mirror. They saw their faces in the mirror for the first time. They boy saw what a handsome face he had and began to boast to his sister about his good looks. She was ready to cry when she saw her own plain face in the mirror. She took her brother's remarks as an insult to her. She ran to her father and told on his brother. She accused her brother for meddling with their mother's things. Their father laughed and kissed them both and said 'My children, learn from now onwards to make a good use of the glass. You, my boy strive to be as good as it shows you to be handsome, and you, my my girl make up your plainness of your features by the sweetness of your character.