The whole Zen literature is a commentary on practice. Actual practice. Your practice.
Before spiritual language degenerates into religion, it is always the effort of a real person, using what is available, to describe their actual experience.
Always the effort of a real person to describe their actual experience. And because we too are that real person, it describes our experience. Not the experience of some far distant moment after decades or lifetimes of practice, but this moment, when we drop the familiar dualities of self and world, mind and body and so on. The language is often shocking and startling because it needs to be, to knock us out of our habitual configuration of experience around a ‘Me’.
For example, the writer Douglas Harding describes Zazen as being like having no head. He doesn’t mean that cognition, sensation and so on disappears. But rather that we lose the sense of this experience as mine. So rather than locating this aliveness within a space called me, there is just this aliveness, which fills everywhere.