Mirrors: Folklore, Beliefs, and Superstitions

An early 20th century Hallowe'en greeting card
(Photo credit: Wikipedia)

Branching out from another thread, I’m posing this as a discussion topic.

Mirrors. They come up an awful lot in various traditions, magical and non-magical uses, and superstitions. They are mentioned in terms of luck (i.e. breaking one resulting in bad luck), magic, divination (scrying), communing with the spirits (ancestors, ghosts, what have you), and sometimes even in terms of seeing through to another realm or seeing your “other half.”

I’m curious about the experiences and wisdom of other people, so consider this the thread to share your opinions, experiences, knowledge, and understanding of mirrors and all they entail in a magical/spiritual manner.

I know it’s a little vague as to a topic direction, so here are a few questions to pick and choose from to start the ball rolling:

What are some stories or bits of knowledge you’ve come across regarding mirrors or reflections that have stuck with you over the years (or an appropriate time frame to count as memorable)?

What is your opinion or experience regarding working with mirrors magically (communing with spirits, spellwork, divination)?

Do you put credit to the idea that breaking a mirror results in bad luck? And if so, what are your thoughts on methods to reverse or mitigate that bad luck?

What is your opinion regarding the idea of a mirror being a portal to another realm of existence? Or even a window into seeing your shadow self?