WHY do mirrors change left to right, but not up to down? Th | Why?

WHY do mirrors change left to right, but not up to down?

The mirror is not aware of your position; it simply reflects the light that hits it. Then why, when the reflected light hits your eye's photoreceptors, does your image change from left to right?

Actually, the question of what makes the horizontal axis so special in the context of a mirror is itself incorrect. The fact is that the mirror does not reflect from left to right or top to bottom, but it does reflect backwards.

In other words, your mirror reflection is not reversed, but inverted into the third dimension, like a glove being turned inside out.