Ta-mei Fa-chang (752-839) was a Chinese Ch'an master. After he got awakened under the Great master Ma-tsu Tao-i (709-788), he went to the Ta-mei mountain and resided there.
One day there was a traveling monk who got lost in the Ta-mei...
THE GATELESS GATE - Chapter 38. Buffalo Passes the Window
三十八 牛過窓櫺 | hide chinese .
show chinese | 五祖曰、譬如水牯牛過窓櫺、頭角四蹄都過了、因甚麼尾巴過不得。
Goso said, "A buffalo passes by the window. His head, horns, and four legs all go past. But why can't the tail pass too?"
Mumon's Comment 無門曰、
If you make a complete about-face, open your eye, and give a turning word on this point, you will be able to repay the four kinds of love that have favored you and help the sentient beings in the three realms who follow you. 其或未然、更須照顧尾巴始得。
If you are still unable to do this, return to this tail and reflect upon it, and then for the first time you will realize something.
Passing by, it falls into a ditch;
Coming back, all the worse, it is lost.
This tiny little tail,
What a strange thing it is!