Words from Our Ancestors:

A monk asked Zhaozhou, "Does a dog have Buddha-nature or not?"

Zhaozhou said, "Mu."

This one word "mu" is a knife to sunder the doubting mind of birth and death. The handle of this knife is in one's own hand alone: you can't have anyone else wield it for you; to succeed you must take hold of it yourself. You consent to take hold of it yourself only if you can abandon your life. If you cannot abandon your life, just keep to where your doubt remains unbroken for awhile: suddenly you'll consent to abandon your life, and then you'll be done....You won't have to ask anyone else...

During your daily activities twenty four hours a day, you shouldn't hold to birth and death and the Buddha Path as existent, nor should you deny them as nonexistent. Just contemplate this: A monk asked Zhaozhou, "Does a dog have Buddha-nature or not?" ZhaoZhou said, "Mu."

 - from a letter of Dahui to a student in Swampland Flowers translated by Christopher Cleary

Words from Don:

We make use of the expedients passed down in our tradition: 'sayings', koans, encounter dialogues, poems. We engage with, inhabit, enliven them in our practice. The process does not require anyone else's presence or permission. As Yasutani reminded us, "You sit alone, You awaken alone, You die alone." 

The great matter of birth and death is your matter to resolve. No one else can do it for you; no teachings will settle it; guidance can be reduced to "let go of false thinking."

"You can not grasp it; you can not reject it."

 -From Hilo Zen Circle Newsletter

Guishan Lingyou (771-853)

Kuei-shan asked Yun-yen

“What is the seat of enlightenment?”

Yun-yen said,

“Freedom from artificiality.”

The Sutra says, 'To behold the Buddha-nature one must wait for the right moment and the right conditions. When the time comes, one is awakened as from a dream. It is as if one's memory recalls something long forgotten. One realizes that what is obtained is one's own and not from outside one's self.' Thus an ancient patriarch said, 'After enlightenment one is still the same as one was before. There is no mind and there is no Dharma.'

One is simply free from unreality and delusion. The mind of the ordinary man is the same as that of the sage because the Original Mind is perfect and complete in itself. When you have attained this recognition, hold on to what you have achieved."

One day Master Kuei-shan Ling-yu came into the assembly and said: 
"The mind of one who understands Ch'an is plain and straightforward without pretense.
It has neither front nor back and is without deceit or delusion.

Every hour of the day, what one hears and sees are ordinary things and ordinary actions. Nothing is distorted. One does not need to shut one's eyes and ears to be non-attached to things.

In the early days many sages stressed the follies and dangers of impurity.

When delusion, perverted views, and bad thinking habits are eliminated, the mind is as clear and tranquil as the autumn stream.

It is pure and quiescent, placid and free from attachment. Therefore he who is like this is called a Ch'annist, a man of non-attachment to things."

During an assembly period a monk asked whether the man who has achieved sudden enlightenment still requires self-cultivation. The Master answered, "If he should be truly enlightened, achieving his original nature and realizing himself, then the question of self-cultivation or non-cultivation is beside the point.

Through concentration a devotee may gain thoughtless thought. Thereby he is suddenly enlightened and realizes his original nature. However, there is still a basic delusion without beginning and without end, which cannot be entirely eliminated. Therefore the elimination of the manifestation of karma, which causes the remaining delusion to come to the surface, should be taught. This is cultivation. There is no other way of cultivation. When one hears the Truth one penetrates immediately to the Ultimate Reality, the realization of which is profound and wondrous. The mind is illuminated naturally and perfectly, free from confusion.

On the other hand, in the present day world there are numerous theories being expounded about Buddhism. These theories are advocated by those who wish to earn a seat in the temple and wear an abbot's robe to justify their work. But reality itself cannot be stained by even a speck of dust, and no action can distort the truth. When the approach to enlightenment is like the swift thrust of a sword to the center of things, then both worldliness and holiness are completely eliminated and Absolute Reality is revealed. Thus the One and the Many are identified. This is the Suchness of Buddha."

https://terebess.hu/zen/guishan.html