I'm thinking too...

I have met people and recognized the hostile me in them. It's like looking at a video of yourself and saying "I have to make some changes"

It jolted my memory of a poem I had taped inside my medicine cabinet for close to 20 years.

It's not about people as mirror self, but your own mirror image.

It's called "The Man in the Glass"

last verse goes something like this

"You may fool the whole world down the pathway of years
And get pats on the back as you pass,
But your final reward will be heartache and tears
If you´ve cheated the man in the glass"