Zen Teachings of Fo-yen
Sermons by Chinese Zen Master Fo-yen Ching-yuan (1067-1120): (excerpts)
(Thomas Cleary, "Instant Zen: Waking Up in the Present". North Atlantic Books, Berkeley, 1994)

There is no particular pathway into it. If your own self is clear and everything is It, when you visit a teacher you do not see that there is a teacher; when you inquire of yourself, you do not see that you have a self. ... When you see in this way, are you not independent and free?
Here, I am thus every day, thus all the time. But tell me, what is "thus"? Try to express it outside of discriminatory consciousness, intellectual assessments, and verbal formulations. This reality is not susceptible to your intellectual understanding. ... How can you think of your original mind? How can you see your own eye? ... What can be seen by the eye or heard by the ear can be studied in the scriptures.
But what about the basis of awareness itself -- how do you study that?
I will settle something for you right now: the ultimate rule is to see your own mind clearly. An ancient said, "The mind does not know itself, the mind does not see itself." So how can you see it clearly? Mind does not see mind; to get it, you must not see it as mind.
Do you want to understand? Just discern the things perceived; you cannot see the mind itself.
All that is necessary is that there be no perceiver or perceived when you perceive [no separation of perceiver and perceived], no thinker or thought when you think [no separation of thinker and thought]. Buddhism is very easy. Just let go, then step back and look.
How about when they say the sound of the rain has given you a sermon? Is that correct? I do not agree; the sound of the rain is you giving a sermon. But do you understand? Clarify it directly; then what else is there?
There is nothing in my experience that is not true. If there were anything at all untrue, how could I presume to guide others? As for you, obviously there is something not true; that is why you come to someone to find certainty.
Where is your mistake? Fundamentally not understanding [nobody does originally], you then seek understanding. Since you basically do not understand, what are you capable of doing? Look to see where the not understanding comes from. Do you want to know? This non-understanding of yours basically comes from nowhere. Since it comes from nowhere, how could this not understanding be? And when you understand, the nonunderstanding goes nowhere.
If you know that falsehood is fundamentally the path, then there is no falsehood in it. Therefore those who master the path have no attainment. Just do not seek elsewhere, and realise there is no confusion or falsehood; this is called seeing the path. The path is inherently always out in the open. Thus for those who attain the path, there is nothing that is not it.

Another book has a chapter on Zen Master Fo-yen:
(Thomas Cleary, "Zen Essence: The Science of Freedom". Shambhala Publications, Boston, 1989)
... Scripture also says [Diamond Sutra], "All appearances are illusory.
If you see appearances are not the same as true characteristics, you see where enlightenment comes from [you see the Tathagata]."
An ancient Zen master said, "if you deny appearances as you see them, you do not see where enlightenment comes from [you do not see the Tathagata]."
Just step back, stop mental machinations, and try to become aware of all the implications of these sayings. If you suddenly see through, how can you be affected by anything?
When you see, let there be no seer or seen; when you hear, let there be no hearer or heard; when you think, let there be no thinker or thought [no separation of seer and seen, of hearer and heard, of thinker and thought].
Buddhism is extremely easy and saves the most energy. It's just that you yourself waste energy and cause yourself trouble. The ancients saw people helpless, and told them to try meditating quietly. This was good advice, but later people didn't understand what the ancients meant, and closed their eyes, suppressed body and mind, and sat like lumps waiting for enlightenment. How foolish! [You must not just sit: you must also realise that the one sitting, i.e. you, is your only teacher.]