Looking for a Cow on the Very Cow

Monk Soyo was clever from his childhood and learned a lot of Sutras, so he became a famous teacher of Sutra. However, he was not sure he would be delivered from life and death, so he went to the great zen master Seosahn to learn Dharma. From then, he learned each Sutra phrase day by day from Seosahn. The phrases had been familiar to him long before. However, he kept learning them for 3 years and was frustrated. One day when he came back from outing for a while, he noticed that Seosahn was hiding an old small book into his inner pocket, stopping to read it. This happened often. When Seosahn fell asleep, Soyo tried to steal and read it. However, Seosahn woke up startled and hid it more secretly. Soyo was angry at last and decided to leave. Then, Seosahn said, "If you want to leave, please do with this book you wanted." There was a Buddhist song in the book like this :

Cut a tree having no shade,
and burn down foams in water.
What a laughing stock, you mounted on a cow,
trying to look for a cow on the very cow.

Soyo went to southern part of Korea with the book and meditated the song for 20 years, but in vain. When he was 40 years old, he went to Mt. Myohyang to look up Seosahn. Then, tears flowed from his eyes. He had never been able to forget his teacher for so many days. Seosahn said, "How is it going ? Did you get it ?" Soyo said, "I don't understand the song yet."

Then, Seosahn said, "What a laughing stock, you mounted on a cow, trying to look for a cow on the very cow." Just then, Soyo became fully enlightened.