Emperor Wu Questions Bodhidharma (BCR1)(BS2)

KOAN:

Emperor Wu asked the great teacher Bodhidharma, “What is the first principle of the holy teaching?”
Bodhidharma said, “Vast emptiness, nothing holy.”
“Who are you, standing here in front of me?” asked the Emperor.
“I don’t know,” said Bodhidharma.
The Emperor didn’t understand.
Bodhidharma crossed the river and went into the Kingdom of Wei.
Later, the Emperor asked Duke Zhi about this. The Duke said, “Your Majesty, do you know who that was?”
“I don’t know,” said the Emperor.
“That was the bodhisattva Guanyin, bringing the mind seal of the Buddha.”
The Emperor was filled with regret and wanted to send a messenger to ask Bodhidharma to come back.
The Duke said, “There’s no point, Your Majesty. Even if everyone in the country went after him, he wouldn’t return.”

—Blue Cliff Record Case 1, & Book of Serenity Case 2 (translation by John Tarrant & Joan Sutherland, titled: Bodhidharma, the Buddha-Heart Emperor, and the Magical Duke)