Tyson describes the mirror as a "psychic window" that can be used both to see things (scrying) and to send energy or messages out.
Donald Tyson's book, , is a detailed guide for anyone interested in the art of scrying and building their own "black mirror" . First published in 1990, it’s often seen as a staple for modern magicians because it bridges the gap between old-school history and hands-on practice. The Core Story Donald Tyson – How To Make And Use A Magic Mirror
The book isn't a fictional story, but it tells the "biography" of a magical tool. Tyson argues that while modern culture sees mirrors as simple objects for checking our hair, they have a long, mystical history as doorways to other places. He breaks the experience down into three main parts: Tyson describes the mirror as a "psychic window"