Xuefeng's What's This? (BCR51)

KOAN:

Once when Xuefeng was living in a hermitage, two students came to pay their respects.
When Xuefeng saw them coming, he slumped against the hermitage door and then came out.
He asked, “What’s this?”
One of the students said “What’s this?” back to him.
Xuefeng hung his head and returned to the hermitage.
Afterwards, the students went on to Yantou.
Yantou asked, “Where have you come from?”
“From Lingnan,” one student replied. “Did you get to see Xuefeng?”
“I did.”

“What did he have to say?”

The student told the story.

Yantou asked, “Then what did he say?”

“He didn’t say anything; he hung his head and went back inside.”

Yantou said, “Too bad! I’m sorry that years ago I didn’t tell him the last word.
If I’d told him, no one in the world would be able to touch old Xuefeng.”
This student stayed through the end of the summer retreat,
and for the second time recounted the story and asked for help with it.
Yantou asked, “Why didn’t you ask me earlier?”
“It’s not as easy as that.”
Yantou said, “Although Xuefeng and I were born on the same branch,
he won’t die on the same branch as me.
If you want to know what it’s all about: ‘It’s just this.’”

—Blue Cliff Record Case 51

(transl. by John Tarrant & Joan Sutherland)