From: The Wisdom of the Desert Fathers
There were three friends who were eager workers, and one of them chose to devote himself to making peace between people who were fighting in accordance with “Blessed are the peacemakers.” The second chose to visit the sick. The third went off to live in tranquility in the desert. The first toiled away among the human quarrels of men, but could not resolve them all, and so he went to the one who was looking after the sick, and he found him flagging too, not succeeding in fulfilling the commandment. So the two of them agreed to go and visit the one who was living in the desert. They told him of their difficulties and asked him to tell them what he had been able to do. He was silent for a time, then he poured water into a bowl and said to them, “Look at the water.” It was all turbulent. A little later he told them to look at it again, and see how the water had settled down. When they looked at it, they saw their own faces as in a mirror. Then he said to them, “In the same way a person who is living in the midst of people does not see his own sins because of all the disturbance, but if he becomes tranquil, especially in the desert, then he can see his own shortcomings.”
Moral of the story: In order to change the world, begin with yourself.