In Shobogenzo, Sammai-O-Zammai, Master Dogen offers a suggestion on how to apply ourselves to meditation while sitting. He says:
We should investigate: at the very moment we are sitting, are all realms vertical? Are they horizontal? At the very moment we are sitting, what about that sitting? Is it a flip? Is it “brisk and lively”? Is it thinking? Is it not thinking? Is it making? Is it without making? Are we sitting within sitting? Are we sitting within body and mind? Are we sitting having sloughed off “within sitting,” “within body and mind,” and so on? We should investigate one thousand points, ten thousand points, such as these.
Translated by Carl Bielefeldt
Yes! This is exactly how practitioners with genuine aspiration apply themselves to Zen meditation. Looking deeply, examining exhaustively, not only our own perspective but that of "all realms."
Master Dogen is not alone; all of the outstanding figures of Zen history testify to the eternal quest that is the source of what, who, where, when, how, and why---the very essence and function of the vast unnamable fathomless void. Zen meditation (Zazen) illumines the wonder and mystery of being alive.