A technique for using a mirror to achieve astral projection. It was described by Dion Fortune this way:

"The big mirror is the doorway to the higher planes. We hang on it the symbol of whatever force we are working with, and shift the other symbols around accordingly. . . "

"How do we go through the astral temple?"

"Through the mirror."

"I see. So that's what the big mirror if for, is it?"

"Yes, this is what we call the mirror working. It is much easier to see psychically in a mirror than in the actual room, and one can build the astral images in the mirror and the crystalline structure of the glass will hold the magnetism. . .."

Pgs. 128-129, Moon Magic, by Dion Fortune, London, Aquarian Press, 1956