"[...] Question.—Can the beginner at once proceed to the contemplation of non-Being? Answer.—By no means! He must by stratagems gradually enter in. I have never yet seen one who straightway
achieved the vision of non-Reality. If for example he were meditating in this room he must first banish from his mind every part of the world except the city of Ch’ang-an. Next every building
in the city except this monastery. Next, every room in the monastery except this cell, every object but himself, every part of himself except the end of his nose. Finally the end of his nose
hangs in space like a drop of dew and on this nose-end he concentrates his mind. This is only a preliminary exercise. There are others of the same kind. For example—persuade yourself that your
navel is a minute rivulet running through[...]".