Dongshan’s Jewel Mirror Samadhi (BCR13)

KOAN:

The teaching of suchness, intimately given by the buddhas and ancestors—
now that it’s yours, keep it well.
A silver bowl filled with snow; a white heron hidden in the moonlight—
Apart, they seem similar; together, they’re different.
The clear-sighted person falls into a well.
What is the sword so sharp it cuts a hair blown against it?
Each branch of coral holds up the moon.

– Blue Cliff Record, Case 13