From Argus the hundred-eyed giant to the Gorgons whose faces would turn a beholder into stone, Greek mythology is a story that's told through the eyes. It's no surprise then that mirrored images play a prominent role in some of the most famous Greek myths. The best-known example is that of the beautiful Narcissus, who fell in love with his own water-reflected image. But it was Perseus who made the cleverest use of a reflection: in combat with the Gorgon Medusa, Perseus watched her reflection in his polished shield and thereby cut off her head without becoming a statue.
In Japanese myths, the gods themselves are tricked by reflection. In one famous story, Amaterasu, the Shinto sun goddess, hides in a cave from the noise of her storm-god brother, and refuses to come out. Lured out by laughter and dancing, Amaterasu sees her reflection hanging from a tree, moves closer, and is seized by the gods and returned to the sky.
Mirrors of black obsidian (a shiny volcanic glass) played a central role in the mythology and religious rituals of the Aztecs, aka Mexica. The name of the Aztec god of rulership and sorcery, Tezcatlipoca, means "the smoking mirror." He was often portrayed with a smoking mirror in place of the right foot lost while battling the Earth Monster. Aztec magicians would divine the future while looking into the black obsidian reflections.
The Aztecs weren't the only ones using black obsidian mirrors for divination. John Dee, an astronomer, occultist, and court astrologer to Queen Elizabeth I of England, also used black obsidian from Mexico to transcribe communications from angels.
The art of divination by mirror is known as catoptromancy. It was practiced for many centuries and is the origin of much folklore. Pére Cotton, confessor to King Henry IV of France (and a contemporary of John Dee), used a magic looking glass to ostensibly reveal plots against the king. The Romans claimed that catoptromancy originated in Persia, but it's known that Pythagoras, the famous 6th century B.C. Greek mathematician, practiced catoptromancy during a full moon.
That whole "vampires don't appear in mirrors" thing? It's not true folklore. Bram Stoker adapted it for his novel Dracula from folkloric beliefs that they draw souls out of bodies - the historical basis for superstitions such as covering the reflections of the sick.
The belief that saying "Bloody Mary" repeatedly in front of a mirror will summon a murderous female spirit is probably the most persistent of contemporary urban legends. We haven't tried it, as we prefer to drink our Bloody Marys rather than recite them, but we find this and all of the history surrounding mirrors to be peppered with interesting stories. We hope you agree.