Write a letter to your mirror and imagine your mirror writing the same letter to another mirror. Imagine it was a very old letter and it was a very old mirror too, it was a black mirror, pitch black, and the letter and the mirror were so old, that no one can remember having ever seen this letter before, so old, that no one can remember, so old that it could neither be dreamed nor imagined, so old that it could never be told.
Pretend to write this letter to your mirror imagining your mirror writing it to you, but there was no mirror in this letter, in this mirror and in this world, you were alone, all alone, by yourself, it took a long time until you finally became a really old creature, so old, that no one even remebered you any longer, then all of a sudden, unprepared you jumped right out of the mirror into the letter.
Now imagine a portal the size of your eyes. Imagine this portal to be located in the midst of your brain, right beside your mind next to your imagination and fantasy, imagine this portal to be called the mirror gateway. Imagine you were able to look through this portal out of your eyes and read your own letter.