There was once a monk who would carry a mirror where ever he went. A priest noticed this one day and thought to himself “This monk must be so preoccupied with the way he looks that he has to carry that mirror all the time. He should not worry about the way he looks on the outside, it’s what’s inside that counts.” So the priest went up to the monk and asked “Why do you always carry that mirror?” thinking for sure this would prove his guilt.
The monk pulled the mirror from his bag and pointed it at the priest. Then he said “I use it in times of trouble. I look into it and it shows me the source of my problems as well as the solution to my problems.”