"In Dropping Ashes on the Buddha we find the story of Won Hyo, the most famous monk of his time in Korea. Won Hyo Sunim one day went to visit the great Zen Master Dae An. Before arriving at the Zen Master’s mountain cave, Won Hyo already heard his beautiful chanting. Upon arriving at the cave he was chagrined to find the old man crying bitterly over the corpse of a dead baby deer. Since the Buddha taught dispassion, as expressed in the Four Great Vows, how could this highly enlightened man be so upset over the death of a deer? Won Hyo asked the Zen Master to explain what had happened. The old monk said that the mother deer had been killed by some hunters, and he had tried to save the baby deer by feeding it milk which he obtained by begging from the nearby village. Because people would not give milk for an animal, he lied that it was needed for his son. “A dirty monk,” they would say, but some would give milk. After a time, however, the nearby villagers refused to give him more milk. He had to go further, and further, and finally after obtaining a little milk, he returned three days later to his cave to find the baby deer already dead from hunger. “You don’t understand,” said the master. “My mind and the fawn’s mind are the same. It was very hungry. It wants milk, I want milk. Now it is dead. Its mind is my mind. That’s why I am weeping. I want milk.” Won Hyo began to understand this man’s great compassion and became his student."

https://kwanumzen.org/teaching-library/1991/07/01/passionate-zen