You only see a reflection. More insight in what is going on behind the mirror.
The mirror tells me lies
Could I mistake myself for someone
Who lives behind my eyes?
Will he escape my soul?
Or will he live in me?
Is he tryin' to get out or tryin' to enter me?
Then there is refracted and reflected light from outside that can alter perception.
If the sun wasn't shining, then I wouldn't exist.
