My "teaching" on how to realize the living truth of Zen in a single day is simple, profound, and yet it is also delightful. Here it is again:
Raise Ki by doing something active (walking, cutting wood, making love, whatever), put your body into a fine cool sweat, let the heat rise to your head, then use that heightened energy to "cut off thinking" in a single instant by "sinking mind into the Tanden." Then you will know everything directly and clearly, in blazing mysterious awareness.
Do this over and over again until you develop the ability to remain in this no-mind no-thought blazing mysterious awareness for just as long as you like. It's refreshing! Deepen it, play in it, enjoy it! Let yourself be elevated, let yourself be sunk, let yourself be edified, let yourself be terrified -- so long as you don't give rise to thinking about what it "is" or "isn't."
This is the classic method of T'ang Dynasty Zen, which I rediscovered all by myself, and practiced all by myself every single day for many years before I ever dared to speak to anyone about it, because I wanted to verify that it is real and profound and liberating and inexhaustible, and it is, so now I am giving it to you. As Great Master Lin-Chi said:
Fellow believers, when it comes to this, where the student is exerting all his strength, not a breath of air can pass, and the whole thing may be over as swiftly as a flash of lightning or a spark from a flint. If the student so much as bats an eye, the whole relationship could be spoiled. Apply the mind and at once there's differentiation; rouse a thought and at once there's error. The person who can understand this never ceases to be right before my eyes.There are not many people who can "cut off thinking" without any practice and some direct pointers like Lin-Chi's (or mine). If I am somewhat outspoken on this matter it is because I constantly run into idiots who insist that they don't need to experience this blazing mysterious awareness because they already fully understand it from reading a Zen book.
Raising Ki and "sinking mind" into the Tanden in the way I describe is the simplest way to "cut off thinking" -- the one and only Zen practice advocated by Great Master Huang-Po. Why should you cut off thinking? Simple. Because you cannot experience life and think about life at the same time. You cannot taste the water in your mouth and chemically analyze it at the same instant. You cannot do Zen while talking about Zen and forming ideas about Zen.
The result of energetically "cutting off the way of thinking," if one maintains clear awareness, is a powerful ease and bliss. One thereby instantaneously enters into the mysterious pure brilliance of nature in a great burst of laughter, and subsequently, as Master Mumon says, one "lives out one's life in a merry and playful samadhi."
Whatever technique helps to give you a direct introduction to your original nature is a Zen technique -- arousing energy by walking in the mountains then "cutting off thinking," shouting, hitting with a stick, composing a poem, practicing with a sword are all energetic Zen techniques. They are energetic because life itself is energy, and Zen is not something apart from life.
Like Master Mumon Ekai, I must now admit to you that I have already said too much. Even one sentence would have been too much. Accordingly, I am now entering a new phase of my "teaching" which will give me the great relief of discarding the word "Zen" along with any verbalization whatsoever, because if anyone asks me a question about any of this I will play a note on my bamboo flute to answer.