The reference to the mirror is derived from divination. Folk used mirrors, water, flames, jet (stone) to gaze at and let the ocular muscles relax, which blurs the vision and removes one of the senses. A modern more ‘science’ based practice is sensory deprivation, using white noise, occluders . Whether mirror or not the idea is that by reducing, negating or removing one or more senses the brain/mind tries to compensate by altering brain wave forms which activate areas of the mind related to psychic phenomenon, (no opinion either way) or in the piece that follows the imagination .
In poet speak it helps open doors.
Clearly the following is not to be taken literally, the shade, ghost writer is part of oneself, muse or whatever . But then you knew that !
I will sit in front of a mirror benign
and stare past that facade of mine
and let focus reduce sight into blur
invoking my shade his magic to stir.
As colour swirls his presence is felt
and words, images and memory melt
into prose and verse which he cleaves
into beautiful poetry before he leaves.