Whoever invented mirror I think was trying to show clear image of human to self. Because image on the water on the glass or anything else that has reflation doesn't show the real personality of each individual to his or herself!
If we were able to brave enough to look at our self only for half an hour everyday and think of what we do what we say and how we do it it will scare off enough to not be the same person tomorrow. I think they try to invent mirror to enjoy life here as a paradise but we misused the purpose of mirror. That's all.