I found myself recalling the story of the T’ang Dynasty artist Wu Tao-Tzu, who is said one day to have gathered his friends to show them his most recent painting. The friends huddled round it in admiration: it was a vertical scroll painting of a mountainous landscape with a footpath that led along the bank of a stream, and then through a grove of trees to a small cottage or hut. But when the friends turned to congratulate Wu Tao-Tzu, they realized he had vanished. Then they saw that he had stepped into the landscape of the painting, and was walking along the path and through the grove. He reached the entrance to the hut, and on its threshold he paused, turned, smiled, and then passed through the narrow doorway.