OK, let's see the case of the hundred-foot pole.
Sekisõ Oshõ asked, "How can you proceed on further from the top of a hundred-foot pole?"
Another eminent teacher of old said, "You, who sit on the top of a hundred-foot pole, although you have entered the Way you are not yet genuine. Proceed on from the top of the pole, and you will show your whole body in the ten directions."(
The Gateless Gate, Case 46)
Here's a small collection of commentaries for a start.
See T'aego Pou chip, 91: "Beneath this great doubt, one must let go of both body and mind." Hakuin later reified this experience as a specific stage in practice; see Kasulis, Zen Action/Zen Person, 112-116. Dogen (1235-1237) relates this "casting off of body and mind" to the final leap off the hundred foot pole; see A Primer of Soto zen: A Translation of Dogen's Shobogenzo, trans. Reiho Masunaga (Honolulu: University of Hawaii Press, 1971), 93-94.(Robert E. Buswell, Jr.: The "Short-cut" Approach of K'an-hua Meditation in Sudden and Gradual: Approaches to Enlightenment in Chinese Thought, p. 374: note 137 to a paragraph on p. 355 that is about the explosion of great doubt resulting in "his own personal destruction")
What does "the top of a hundred-foot pole" mean? Figuratively, it is the stage of complete emptiness. When you attain self-realization, your eye will open first to the state of consciousness where there is absolutely nothing. That stage is called the "great death." It is a stage where there is no dualistic opposition such as subject and object, good and bad, saints and ordinary people and so on. There is neither one who sees nor anything seen. Zen usually expresses this stage with the words, "There is not a speck of cloud in the spacious sky."
Anyone who wants to attain the true Zen experience must pass through this stage once. If you remain there, however, you will be unable to attain true emancipation from deep attachment to this emptiness. This stage is often referred to as the pitfall of emptiness. It becomes a kind of Zen sickness.
When we attain kensho, we come to the top of the high pole where most of us are seized with this malady. It is said that even Shakyamuni succumbed to it for two or three weeks after his great enlightenment. The Zen master in this koan warns not to linger at this point when he says, "Take a step forward from this stage and you will be able to manifest your whole body throughout the world in ten directions." That means that you must become completely free from all kinds of attachments.
Look at this stick, this kotsu. See, it is lying horizontally at first. This position represents our ordinary life. With the practice of zazen, working on Mu or counting our breath, one end of the stick will gradually come up, while the other is fixed at the original point. When the stick stands perfectly vertical, that is the state of complete emptiness. There you become completely one with Mu, and ther eis no concept of thought whatever in your mind. This is the great death. It is also the entrance to perfect enlightenment. This stage is void of mental activity. But you must not stop there. You must press on even harder. Then the top of the stick will move forward, and suddenly a whole new world will manifest itself! This is true enlightenment. Perhaps now you understand what this warning means.
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In our present koan, the last phrase of the case reads: "...to manifest this whole body throughout the world in ten directions." This means you will realize that you are one and alone in and with the whole universe and that you should be able to do anything in an extremely free and positive way. That is the state of true enlightenment.(Kōun Yamada: The gateless gate - the classic book of Zen koans, p. 217-218)
This state beyond hope, where "there is no place to put one's hands and feet," Ta-hui remarks, "is really a good place." It is a "good place" because it is there that conceptualization is brought to and end: "Without debate and ratiocination they are at a loss, with no place to put their hands and feet." Only then can the student make the all-important transition from the conditioned to the unconditioned, which is likened to a death-defying "leap off a hundred-foot pole." One need only recall the role of no-thought as the access to final realization-awakening to see how thoroughly that earlier account of meditation has been subsumed by the hua-t'ou technique.
The leap off the hundred-foot pole from the conditioned to the unconditioned is perhaps the quintessential expression of what Ch'an means by a sudden style of cultication and meditation. Sudden cultivation demands that there be no hint of any sequence of practices that would lead the student from one stage to another, progressively abandoning defilements and cultivating wholesome actions, until he achieves perfect purity of mind. The jump off the hundred-foot pole suggests the radical nonattachment, even to one's own body and mind, that Buddhism has always expected as a prerequisite to enlightenment. Ch'an does not deny that it might take time for one to build up the courage necessary to take that ultimate plunge. But its lack of sequence at least freed it from charges of being gradualistic.(Robert E. Buswell, Jr.: The "Short-cut" Approach of K'an-hua Meditation in Sitting with Koans: Essential Writings on Zen Koan Introspection, ed. John Daido Loori, p. 83)
The top of the hundred-foot pole is the isolation of Hui in a selfless condition. He has experienced one side of the complementarity of form and emptiness, but he has not integrated the two aspects of reality for himself, as himself. Even after meeting the great Nan-ch'üan, he is still stuck in the void.
"Take a step from the top of the pole." This is the test point of the case, which students through the centuries since Ch'ang-sha have presented to their teachers. For our purposes, we can see how Ch'ang-sha is emphasizing the importance of moving on from simple awareness of the unsubstantial nature of the self and all things. With that step, "worlds of the ten directions will be your entire body." That is, you will find mountains, rivers, the great Earth itself, the sun, the moon, the stars, people, animals, plants, streets, and towers to be your own great self.(Robert Aitken: Original Dwelling Place - Zen Buddhist Essays, p. 91)
The need to go beyond the way of knowing of the Great Perfect Mirror is also emphasized in many koans. For example, in koan number 46 of the Mumonkan, Zen master Sekiso asked, "How will you step from the top of a hundred-foot pole?" And another eminent master of old said, "You, who sit on the top of a hundred-foot pole, although you have come to realization, you are not yet real. Go forward from the top of the pole and you will manifest your whole body in the ten directions." Manifesting your whole body in the ten directions is this second awakening. It is seeing that all things in the six fields of sense - seeing, hearing, discernment, and knowledge - are your own awakened nature.(Albert Low: Hakuin on Kensho, p. 59)
This "backward step," at once the casting off of body-mind and presencing of the original face, is fundamentally the same as advancing a step further from the top of a hundred-foot pole. When one takes one more step from the top of a hundred-foot pole and jumps into empty space, one immediately realizes that the boundless empty space is oneself, one's true Self that is nondual with others. It is precisely "the Self prior to the universe's sprouting any sign of itself" (chinchō mibō no jiko).(Masao Abe: A study of Dōgen - his philosophy and religion, p. 144)
Dogen instructed:
Students, cast aside your bodies and minds and enter fully into Buddhism.
An old Master has said: "You've climbed to the top of a hundred-foot pole. Now keep on going." Most people, when they reach the top, are afraid they will lose their footing and fall to their deaths. Thus they hang on all the more tightly. To advance another step means to discard all thoughts of everything, from your functions as a savior of other beings to the means of your own livelihood, even if it requires casting away your own life. If you do not do this and even if you study the Way as earnestly as though you were trying to put out flames in your own hair, you will not be able to attain the Way. Resolve to cast aside both body and mind.(A primer of Sōtō Zen: a translation of Dōgen's Shōbōgenzō zuimonki, 3.1, p. 49)