Universal Promotion of the Principles of Zazen by Dogen Zenji

In his summary of this fascicle, Mushin offers another koan for us to be with:

#6″Hard to sit.   Think of not thinking.  How do you think of not thinking?   Non-thinking.  This is in itself the essential art of zazen.  Maintain this one Buddha-mind seal.  It’s Shobogenzo, the treasury of the true dharma eye and subtle mind of nirvana.”