Talk about being willing to 'give one's right arm' to study the Dharma! (Actually, the legend says the 'left' arm, and may actually be based on the biography of a completely different master who had his arm cut off by bandits during a robbery. Cutting it off oneself to show one's determination makes a better fable).
We sit with the mind 'like a wall' ... stilling conditions outside, no grasping of mind inside, and not even thought of 'inside' or 'outside' the wall ...
But do not think of this "wall" as some thing dead and dull as a pile of bricks, or the thick and confining walls of a prison. Rather, it is clear, alert and ever bright, very much vibrant and living. As Keizan says, trying to "become mindless like a wall ... is not the intimate experience of the Mind. [Thus Hui-K'o] said 'I am always clearly aware'. If you can become like this, then this is what the Buddhas have realized."
I also greatly appreciate the end of the story, as the Enlightened Ancestor chooses, for his own reasons, to return to the village and marketplace, to spend his last years "sometimes entering wine shops, sometimes engaging in street talk, sometimes joining workers who empty the privies."
Cook from 153
Hixon from 138