Guishan's No Foundation to Rely On (BS37)

KOAN:

Guishan asked Yangshan, “Suppose that out of the blue, someone asks you, ‘All sentient beings only have disorderly consciousness, boundless and with no foundation to rely on.’ How would you conduct an inquiry into this?”Yangshan said, “If a student like that came, I’d call, ‘Hey so and so!’
When the student turns her head, then I’d say, ‘What is it?’
Then I’d wait while she thinks about it.
Then I’d say, ‘Not only is disorderly consciousness boundless but also there is no foundation to rely on.’”
Guishan said, “Good!”

—Book of Serenity Case 37