There was once a monk who carried a mirror where ever he went. A priest noticed this behavior one day, and thought to himself, “This monk is so vain and shallow, carrying that mirror around. He shouldn’t concern himself with his external appearance–it is the inside, not the outside that really matters. I’ll teach that monk a lesson today.”
The priest approached the monk and asked, “Why do you always carry that mirror?” Surely, the monk would have to admit his guilt, he thought.
The monk pulled the mirror from his bag, and pointed it at the priest. After a moment of silence, he replied. “I use this in times of trouble. When I look in the mirror, it shows me the source of my problems, and the source of the solution.”