Mirror, mirror on the wall
A look at how a person's inner feelings and desires affect the person's behaviour towards them and can change them possibly forever. Also what influence our conscience has on our actions.
The mirror does not lie
If you want to find your best friend, look in the mirror,
If you want to find your potential worst enemy, look in the mirror,
If you want to which one of the above applies to you, look inside you.
If you want to look inside you, look no further than your heart
The mirror is a reflection of who you are as a person, if only we had a mirror in front of us everytime we start to utter angry words, or hurt people, or do something merely for material or carnal pleasures that is against what we believe in or who we are. That mirror would act as our moral compass, it would direct us back to the proper path, back to our own hearts and our own character, back to our natural course of actions and behaviours.