The influence of others acts even upon the great sages. A sage was sitting in concentration. He said, "There must be some person from outside in the room." The disciples looked, but they could see no one. They saw only the familiar faces, there was no stranger among them. The sage said, "Look again, there is some disturbing element in the room." They looked, and found a stick that had been left there by a visitor, a person who was hostile. Even his stick had the power to disturb and prevent the concentration.