BUDDHA AND COW DUNG - a Zen Buddhism Koan

The famous Chinese poet Su Tung-po (1036-1100) in the Song Dynasty wrote very simple Chinese Poems based on Buddhist Philosophy, he himself being a very religious person. He was appointed to the position of the Director of Literature for the Imperial Court.
One day he visited a Buddhist Temple and meditated with the Monk Buddhastamp. After a little while, Su asked the Monk: "Look at me. I am sitting here meditating. What do I look like?"
Buddhastamp examined Su closely for a while and said, "Officer, you are very solemn, healthy and gentle. You look like a Buddha Stature." Su was very pleased with the answer.
After a while, Buddhastamp asked Su this time, "Officer, I am sitting here meditating also. What do I look like?"
Mr. Su thought, this Monk always got the upperhand whenever we debated on any subject matters. Now, I got the opportunity to win this time. So, he said, "You look like a pile of cow dung." This time, the Monk just smiled and did not argue with him at all.
Thinking that he had won the debate, Mr. Su went about telling everybody in town how he did it, until his younger sister heard of his story. "My dear brother," said Miss Su, "you had lost the debate completely."
"What!? I am sure the Monk was dumbfound. How come I lost the debate?"
"Dear brother," said Miss Su, "the Monk's heart was filled with Buddha nature, therefore he saw you as a Buddha. But your heart was filled with cow dung, and therefore you saw him as a pile of cow dung."