Here is a little bit of what i know about mirrors.
Dr. Raymond Moody, who has done Research on Life After Death, now has written a book, about meeting Loved Ones, who have crossed over.
The method he uses, has to do with a large mirror, where Spirit Friends, can come from the next dimension, back to visit.
Many of his clients experienced visits from "dead" relatives.
Apparently, this is an ancient method, which was used, i think, back in Greece.
I forget th ename of Dr. Moody's book, but it was published back in the 90's. I am sure you could find a copy at your local library, which is where i found the copy i read.
Or, perhaps Amazon has back copies.
In Feng Shui, I read that to repel evil/bad energy, place a mirror to reflect back this bad chi.
I happened to live in a house, that was at the crossroads of 3 streets.
I found out in this Feng Shui book, that cars, stopping at this intersection and also people, walking at this intersection, could toss bad chi at my house!!!!
Yikes! The next day, I got a mirror and I wired it to my mailbox, and I didn't care what the Postman thought.
I do feel it made a big difference in the vibration of the house.
A woman, who lives in a condo down the street, had a mirror in her living room. She was repelling any negative chi, coming from the building, another condo across the road. Well, there was an Asian woman, very familiar with Feng Shui, and when she saw t his mirror in the first woman's living room - she went across the street, and pleaded with the woman, "Please take that mirror down, you are sending me bad chi." Then she had a litany of all the "bad" stuff that had occurred in her condo.