The mirror is also a symbol of knowledge. The mirror of the queen in the tale of Snow White tell always the truth.
The new wife of the king, the father of Snow White, possesses a magical mirror that answers any question, to whom she often asks: "Mirror, mirror on the wall, who in the land is fairest of all?" to which the mirror always replies "You, my queen, are fairest of all." But when Snow White reaches the age of seven, she becomes as beautiful as the day, and when the queen asks her mirror, it responds: "Queen, you are full fair, 'tis true, but Snow White is fairer than you."

Illustration of the tale of Snow White and the Seven Dwarfs

Avatar Arria Perreault is looking her face on a mirror
English translation of the tale "Snow White" (Germany, Jacob and Wilhelm Grimm)