Master Dogen described zazen as walking at full speed over the heads of demons.
Note the imagery carefully. The demons don’t belong to someone else; they belong to you: their heads live in your head, and you don’t need to be rid of them to be free of them. Yet, they enable the Way to be walked.
Because they don’t live in the vigorous body of practice. Beware the demon of acquisition. Beware the demon of wisdom.
It’s an odd inversion: the body walking over the head. Your head, obviously, but not your body. Rather, the body of the whole universe, expressed through this body.