Here is the Koan:

“What is the blown-hair sword?”

The reply: “Each branch of coral holds up the moon.”

Now a Zen master might ask in helping an explorer penetrate this koan:

Show me the sword so sharp it can cut through all delusions. This is what is meant by “blown-hair sword.”

This koan points to the reflected light of the moon in a single coral branch within a coral community.

How can our community of corals hold up the moon?

You may find useful the explanation of this wonderful koan by my teacher Yamada Koun Roshi. The link can be found below.

Source:

Here is a teisho, an exploration of this wonderful koan by Yamada Koun Roshi.