Master Dogen described the practice of zazen as being the [continuous process of] ‘dropping off body and mind’.
It’s reasonably clear what he meant by dropping off mind, because he describes that process in quite a straightforward way in Genjokoan: in zazen, we allow all our experience to live fully, unconstrained by the assumption of ownership of this experience by the self.
That is, all the multifaceted aspects of our experience can be expressed, and they don’t have to be stuffed into the small jar of self. Sometimes that is expressed in spatial terms. So we’ll say it’s as if in zazen our awareness is like vast space, within which everything can freely appear, manifest itself entirely then go.
And if we do not give attention to the body, people can quite often have the notion that this sense of vast spaciousness, once developed, is the same as non-duality. That if zazen had a destination, this would be it.
Yet that’s incorrect, because it excludes the actual fabric of being; this body and all others.
Dropping off body is more difficult for us to understand, but it needn’t be. It is simply to forgo an unconscious yet pernicious idea we have of the body as being like an object within consciousness.
Or another way of putting it is as being like a pictured body within the mind: when someone asks us to pay attention to our left hand, do we sense it, or do we look at it?
Dropping off body is dropping off that conceptual sense of the body, so we can actually experience it as it is phenomenologically. And what we notice when we’re sitting in zazen is that very often we will experience our body as being like charged space.
So it’s there [as a ‘something’] but not there. And there isn’t a clear boundary between body and world. There’s not a clear demarcation between this body and the body of all being.
And that is a much more immediate and natural sense of non-duality, which is beginningless and endless.