Poem by the 12th century Chinese Buddhist master Hongzhi Zhengjue
All things originate from the mind. When the whole mind is silent, all appearances end. Which is other, which is self? When there is no sign of differentiation, not even a single atom can be established. When not a single thought is born, you penetrate through before the womb and after the skin bag; one point of inconceivable illumination, whole and undifferentiated, without corners, edge or traces that cannot be dimmed. What cannot be dimmed is called inherent knowledge; the point of inherent knowledge is called the fundamental endowment.
When you realize all things are empty you are free in all states of mind and penetrate beyond through every atom of dust. The primordial beam of light pervades everywhere and transforms according to the energies and situations. Everything it meets is the source, subtly illuminating all things. Empty, the wind in the pines and the moon in the water respond outwardly without getting confused. Live in clear harmony, without a wandering mind, not sticking anywhere. With a mind like spring bearing flowers, like a mirror reflecting images; in the midst of floods of tumult, you will naturally stand serene above it all.
When your state is thoroughly peaceful and your livelihood is cool and serene, you will see the emptiness of the ages; there is nothing to be troubled by, nothing that can obstruct. Empty, absolute and radiant; clear, complete and shining; it clearly exists for all ages, never dimmed. If you want to remain tranquil, cover and uphold in the same way as sky and earth -- appearing or disappearing, shutting down or opening up, all are up to you.
Clean, pure, perfectly clear; the power of the eye cannot reach its bounds. Still, silent, empty and vast, the ken of the mind cannot find its edges. One who investigates sincerely and really arrives considers this the fundamental ground; neither buddhas nor demons can enter; neither dust nor dirt can defile it.
There is utterly no way to study this matter; the essence lies in emptying and opening body and mind so they are vast as space, then you will naturally be complete everywhere. This awareness cannot be dimmed, this clarity cannot be confused. The moon follows the flowing waters, the rain goes with the moving clouds. Each and every sense and sensation is immediate and absolute. Therefore it was said that a saint has no self, but there is nothing that is not himself. It is so obvious, so clear; you realize that gathered in or let out, it has become a white bull on open ground, which you cannot drive away even if you try.
Written by the 12th century Chinese Buddhist master Hongzhi Zhengjue. English translation by Thomas Cleary published in Timeless Spring: A Soto Zen Anthology. Found via naturalawareness