Su Tung-po, a scholar of the Imperial Academy, once debated with Ch'an Master Chao-chueh about the Path to enlightenment. During the debate, they touched upon the question of whether both sentient and non-sentient beings could attain perfect wisdom. Inspired by the discussion, Su wrote three poems to express what he had learned. Their titles were "Before Practicing Ch'an," "While Practicing Ch'an," and "After Becoming Enlightened through the Practice of Ch'an." The first poem read as follows: Viewed horizontally, it is a mountain range;    while viewed vertically, it becomes a peak. Far and near, high and low -- each is unique. The real face of Lu Shan is not to be seen, Because one is standing on the mountain. The second poem expressed a different state of mind, while Su engaged in Ch'an practice: The misty rain of Lu Shan and the tides of Chekiang, Not seeing them in person is forever regrettable. After arriving, nothing unusual is to be seen -- The misty rain of Lu Shan and the tides of Chekiang. The final poem described Su's feelings after he had attained realization through Ch'an practice: The sounds of rippling creeks are long, wide tongues; The mountains are the pure bodies of the Buddhas. Late at night, when contemplating the 84,000 verses, How is one to explain what one has realized? After this experience, Su Tung-po thought even more highly of his own understanding of the Dharma. When he was told that Ch'an Master Ch'eng-hao from Yu-ch'uan Temple in Chingnan was so incisive that his timely questions defied response, Su Tung-po refused to believe it. He went to visit the Master in civilian clothing to test the latter's knowledge of Ch'an. As soon as he met the Master, he asked, "I was told that you're very good at Ch'an meditation. May I ask, what is meditation?" The Master did not answer Su Tung-po's question, but instead asked, "Sir, may I have your name, please?" Su Tung-po replied, "My name is Scale, which weighs all the abbots who are on Earth." Upon hearing this, the Master gave a loud shout and asked, "May I ask how much that shout weighs?" Su Tung-po had nothing to say in reply, but simply stood up, prostrated, and left.   In meditations Su Tung-po experienced the three stages described by Ch'an Master Ch'ing-yuan Hsing-ssu: "When one sees a mountain of river before practicing Ch'an, it is simply a mountain or a river. When one sees a mountain or a river during Ch'an practice, it neither looks like a mountain nor a river. When one sees a mountain or a river after practicing Ch'an, it is again a mountain or a river." After progressing through these three stages, one acquires a comprehension of the Dharma, however, one still will not be enlightened, for one has yet to attain a realization of what one has understood through personal experience. In other words, a Ch'an practitioner's self-cultivation starts by comprehending the Truth and is perfected by practicing the Truth. A person who lacks either self-cultivation or realization will surely become dumbfounded and speechless by a shout from Ch'an masters such as Ch'eng-hao.   (Source: Hsing Yun's Ch'an Talk, Book 4)