I have finished at least a rough draft of Letting Go in Action: the Practice of Zazen. The draft never does explain why letting go in action should be considered the practice of zazen but does perhaps offer an explanation of what Gautama’s four trance states have to do with mindfulness of the body. I would welcome any comments.
Here is an excerpt:
In a poem from the fifth century C.E., the Buddhist monk Fuxi elaborated on how relaxed extension stretches the ligaments between the sacrum and the pelvis, and how gravity generates activity in the legs and in the pelvis that frees the experience of location and turns off volitive activity in the movement of breath:
The empty hand grasps the hoe-handle
Walking along I ride the ox
The ox crosses the wooden bridge
The bridge is flowing, the water is still
(‘Zen’s Chinese Heritage’, Andy Ferguson, pg 2)
‘The ox crosses the wooden bridge’ describes an effect of the rhythm of stretch and activity as the weight of the entire body rests in the ligaments that connect the sacrum and pelvis: each step of an ox on a wooden bridge reverberates to the headtop and throughout the body of any rider, from the spine to the surface of the skin, and the same is true for the individual whose weight rests in three directions between the sacrum and pelvis.
The phrase ‘the bridge is flowing’ could be said to describe a moment before sleep when the location of awareness seems to shift in place in the body, while ‘the water is still’ could describe the cessation of volitive activity in the body at that same moment. For most people, the loss of volitive control in the activity of the body is associated with falling, and as a consequence many people experience a ‘hypnic jerk’ or sudden muscular contraction as they begin to fall asleep. Fuxi suggests that an awareness that shifts location freely in the body can come about as a matter of course, as the ability to feel informs the sense of location and the weight of the relaxed body generates stretch and activity in the movement of breath. He depicts a process of gradual stages whereby a muscular contraction is avoided, at the moment when a shift in the location of awareness with a cessation of volitive activity registers in the sub-consciousness.
Although Fuxi outlines the stages of a process, and the process may be said to be gradual, the transition from a waking state to a state between waking and sleeping must be said to be sudden, marked by a sense of location that can shift and a cessation of any voluntary activity in the body.