Shundo David Haye – Zen Priest

‘To transcend the whole universe at once, to live a great and valuable life in the house of the Buddhist patriarchs, is to sit in the full lotus posture. To tread over the heads of non-Buddhists and demons; to become, in the inner sanctum of the Buddhist patriarchs, a person in the concrete state, is to sit in the full lotus posture. To transcend the supremacy of the Buddhist patriarchs’ supremacy, there is only this one method. Therefore, Buddhist patriarchs practice it solely, having no other practices at all. Remember, the universe in sitting is far different from other universes. Clearly understanding this truth, Buddhist patriarchs pursue and realize the establishment of the will, training,the state of bodhi,and nirvana. 

Just in the moment of sitting, investigate whether the universe is vertical, and whether it is horizontal. Just in the moment of sitting, what is the sitting itself? Is it a somersault? Is it a state of vigorous activity? Is it thinking? Is it beyond thinking? Is it doing something? Is it not doing anything? Is it sitting inside of sitting? Is it sitting inside of the body-mind? Is it sitting that is free of “the inside of sitting,” “the inside of the body-mind,” and so on? There should be investigation of thousands and tens of thousands of points like these. Sit in the full lotus posture with the body. Sit in the full lotus posture with the mind. Sit in the full lotus posture being free of body and mind.’ (Shobogenzo
Zanmai-ō-zanmai)

NB: other postures are available.