Li Ao, a government official of Langchou during the T'ang dynasty, greatly respected the virtuesof Ch'an Master Yao-shan Wei-yen.
One day, Li Ao went to visit the Master. When he arrived, the Master was reading under a tree. Although the Master knew that Li Ao had come, he had no intention of getting up to greet him. When his attendant announced the arrival of Li Ao, Master Wei-yen ignored him and continued reading.
Li Ao was irritated and said testily, "What I see here is not as great as what I have heard." He turned around and prepared to leave.
Coldly, Master Wei-hen replied, "Why do you value what you hear and disdain what you see?"
Li Ao was moved by what the Master had just said. Turning around, he apologized and asked, "What is the Buddha's teaching?"
Master Wei-yen pointed upward, then downward, and asked, "Do you understand?"
Li Ao shook his head and said, "No."
Wei-yen said, "The cloud in the blue sky and the water in the jar."
Li Ao was pleased with this response. He bowed and recited the following verse:
(Source: Hsing Yun's Ch'an Talk, Book 2)