Master Chao-chou 趙州(778-897), was asked by a monk, "Does a dog have Buddha-nature?" to which the master replied, "Wu", meaning no, nothing. As kung-ans go, this is a basic one, but possibly the most famous. In some cases, there is no record of an awakening, but the story is remembered because it contains, or expresses, meanings crucial to the understanding of enlightenment. Here is another kung-an, also involving Chao-chou.

Chao-chou had a disciple who met an old woman on the road and asked her, "How do I get to T'ai Shan 臺山 (Mount T'ai)?" She said, "Just keep going." As the monk started off, he heard the old lady remark, "He really went!" Afterwards, the disciple mentioned this to Chao-chou who said, "I think I'll go over there and see for myself." When he met her, Chao-chou asked the same question, and she said the same thing ─ "Just keep going." As Chao-chou started off, he heard the old lady say again, "He really went!" When Chao-chou returned, he said, "I've seen through that old lady." What did Chao-chou find out about the old lady? What is the meaning of this lengthy and obscure kung-an?