After thousands of years, but still centuries and centuries ago, inventors produced mirrors that the common people would regard as magical. These mirrors in particular are mirrors built a certain way that are trick mirrors. With such a mirror, for instance, a slim person can stand in front of that mirror and “magically” see himself or herself as super obese; very widely spread out. Other trick mirrors can make a small person “magically” appear as a tall; elongated person. Those mirrors, also known as distorting mirrors, are curved mirrors, often using convex and concave sections to achieve the distorted effect. Many, many, many years later distortion mirrors were placed in circuses, fun houses, and amusement parks. By then, people knew these mirrors produced illusions through light and optics and not by supernatural means.
Other types of magic mirrors existed throughout time. In the Middle Ages of Europe, the so-called talking mirror was a magic mirror. The most famous speaking mirror of Literature is in the story of “Snow White and the Seven Dwarfs”.
The Snow White story is a very, very old tale that was collected, then retold as part of the Grimm Brothers’ book of over 200 stories published in 1812. In the tale, the wicked queen asks the magic mirror: “Mirror, mirror in my hand, who is the fairest in the land?” The small mirror replies that “”Snow White is the fairest”.
The idea of the talking mirror is most probably based on a security mirror. In a large store, for instance, there is a mirror on a wall or on a door. The mirror appears to be just a regular mirror where you see yourself. But, actually the reflecting glass is part of a hidden room; the mirror is a special type which allows people behind it to clearly see people outside of it and the people outside cannot see at all the security people inside.
But, if a person behind the door spoke loudly enough, a person in front of the mirror would hear the other person and if the bystander did not know the mirror is a see-through mirror with observers inside a room; the bystander, centuries ago, would think the mirror “magically” talked to him or her. This matter is especially true if no security personnel come out of the room to explain what happened.
Royalty in castles, for centuries, most probably had security mirrors, in ‘hidden from the public’ manned rooms. These security personnel could also have watched, in secret, with the knowledge of the royal household, certain actions of workers within the castle.
In the folklore of magic mirrors, there are stories of a person who supernaturally walks through a mirror into another land; another universe. The most famous such story is also a novel entitled “Through the Looking-Glass and What Alice Found There” by the British writer and mathematician Lewis Carroll (Charles Lutwidge Dodgson) published in 1871. The book is a sequel to the novel “Alice in Wonderland” by the same author published in 1865.
On the science fiction space travel show, “Lost in Space” (1965-1968); there is an episode where Penny, her pet chimpanzee and later on Doctor Smith walk through a mirror into another dimension and after various incidents with an alien human looking boy and a furry tall one-eyed monster are able to walk back out of the mirror. This is story number 21 entitled “The Magic Mirror”, with the original air date of February 16,1966.
The idea of a person magically walking through a mirror and then later marvelously walking back out of the mirror is most probably based on a very large, rectangular vertical security mirror (two-way seeing from mirror from the inside room). The mirror is attached to an easily push oriented door, with the knob or hand area part not easily seen, for added security. (An example being the door knob being a color that is the same color as the wooden or metal frame of the mirror door.) If a person pushes the mirror door on the outside and opens the door somewhat and then quickly closed the big mirror door quietly; a person viewing from a distance, not knowing what is going on, can assume someone magically walked through a mirror. The same idea of someone viewing from a distance, not knowing the situation, can see a person exiting and assume someone magically walked out of a mirror.
Over many years, there are magicians who have created elaborate illusions about walking through glass, metal doors, and walls. Videos of such tricks can be seen and heard with the explanations on the internet site YouTube.