Dissolving completely in deep unknowing, one's breathing becomes tranquil and one's mind gradually settled. Your energy becomes clear and sharp, your awareness bright and pure. Observing carefully, inside and outside become empty and pure, and the mind becomes still. From this stillness, the realization of the sage becomes manifest . . . The presently arrived body of true nature is pure, perfect, and complete. All forms are manifested within it, even though that nature is without mental effort. It is like a clear mirror suspended in the air -- all the various objects are manifested within it, but the mirror is without any effort to generate them.
-from the Ju Dao An Xin Yao Fang Pien Fa Men by Master Daoxin, 4th Patriarch of Ch'an