Dogen described zazen as ‘dropping off body and mind’. We can assume that both are dropped off at the same time. I’ve often described this as being a letting go of our habitual sense of self, opening into wide spacious awareness. But we can also consider dropping off body and mind in a sequential way.
Our sense of self is often something like: “I am this mental consciousness located in the brain, which is distinct from the body.” Few people now would explicitly say this, but it doesn’t matter, as it describes how most of us act. Anyway, the idea is obviously dualistic and disembodied.
So we can first drop off the mind by dropping the mind into the body. And we’re only able to do that to the extent that the body is dynamic, alive and joyful. Which is why we place such an emphasis on the posture, because if our posture is right then our body is naturally expressing itself.
So there’s naturally an upward movement of our spine – we don’t require to will it. There’s a natural dropping down of our weight. We’re in a dynamic relationship with heaven and earth.
If we can re-embody our mind, we have our sense of ourselves as this dynamic body (similar to what a baby might experience). And once we’ve done that, then we can drop off the body, because the body experienced in this non conceptual way isn’t separate from everything else.
We let go of a sharp distinction between this body and the greater body of all being. And that’s easy to do because it’s obvious in our actual experience: there isn’t a clear boundary.