The Whispering Legions, 38th Day of Spring, 525 M.E. (Castor): Yaoshan Weiyan (1251-1334 Common Era of my New Revised Universal Solar Calendar, or 731-834 A.D. of your Christian Nationalist calendar) was a Chinese Chan master from what is now Shanxi Province in northern China. He was a student of Master Shitou Xiquan.

One day, as Yaoshan was sitting in meditation, Shitou asked him, "What are you doing here?"

Yaoshan said, "I'm doing nothing."

Shitou replied, "Then you're just sitting leisurely."

Yaoshan said, "If I were sitting leisurely, then I'd be doing something."

 Shitou then asked, "What is it, then, that you're not doing?"

Yaoshan said, "A thousand sages don't know." 

Apparently, Yaoshan couldn't sit in peace without someone coming along and interrupting him. Another story tells of another time when Yaoshan was sitting and a monk asked him, "What do you think about when you sit in meditation?"

Yaoshan said, "I think not-thinking."

The monk asked, "How do you think not-thinking?"

Yaoshan said, "Nonthinking." 

This latter story appears to be one of Japanese Zen Master Dogen's favorites, as he references it numerous times. It's included in his collection of three-hundred koans and in his Eihei Koroku, a collection of sermons and talks. It comes up frequently in his Shobogenzo and there's even a fascicle (Zazenshin) in that book dedicated to it. Dogen pointed out that thinking is linear and sequential - a separation from reality and an abstraction rather than reality itself. On the other hand, not thinking is suppressive  - it cuts away thoughts the moment they arise, making the mind dead and unresponsive.

Nonthinking has no such edges, Dogen posits. It is the boundless mind that neither holds onto nor lets go of thoughts. It is the manifestation of mind in which the dualism of self and other, thinking and not thinking, dissolves. This, Dogen maintained, is the "right thought" of the Buddha.

Yes, as you can probably tell, I've been reading my new translation of Shobogenzo and cross-referencing it with my other Zen texts. After some reading today, I sat down for my alternating-day meditation. For some practical advise on how to approach nonthinking, just sit and attempt to neither engage in your thoughts nor suppress your thoughts. Just observe them as they arise and allow them to fall away on their own. Observe the quiet spaces between thoughts. When you notice you're caught up in some narrative or another, don't beat yourself up over it but just gently detach and observe the narrative and observe yourself noticing the narrative. Observe the space between the narrative and your realization of the narrative. Just sit and watch. Nonthinking.