Hakuin similarly taught that a Zen which ignored society was hollow and meaningless, and its monks of no use to anybody. He was particularly stern with conventional Zen students, who were content in their own enlightenment and ignored the needs of others. "Meditation in action" for the monk meant the same as for a layman, with one significant difference. Whereas the layman could bring meditation to his obligatory life of affairs, the monk must bring the life of the world to his meditation. Just to hide and meditate on your own original nature produces inadequate enlightenment, while also shutting you off from any chance to help other people, other sentient beings. The ancient masters knew, said Hakuin, that a person truly enlightened could travel through the world and not be distracted by the so-called five desires (wealth, fame, food, sleep, and sex). The enlightened being is aware of, but not enticed by, sensual gratification.
The Third Patriarch [Seng-ts'an, d. 606] has said: "If one wishes to gain true intimacy with enlightenment, one must not shun the objects of the senses." He does not mean here that one is to delight in the objects of the senses but, just as the wings of a waterfowl do not get wet even when it enters the water, one must establish a mind that will continue a true koan meditation without interruption, neither clinging to nor rejecting the objects of the senses.15
But Hakuin asked something of a Zen novice even more difficult than that asked by the Chinese masters of old—who merely demanded that a monk reject the world, turn his back, and shut out its distractions. In contrast, Hakuin insists that he meditate while out in the world, actively immersing himself in its attractions. The older Ch'an masters advised a monk to ignore the world, to treat it merely as a backdrop to his preoccupation with inner awareness; Hakuin says to test your meditation outside, since otherwise it serves for nothing. And today Rinzai monks are expected to silently meditate during all activities, including working in the yard of the monastery, harvesting vegetables, or even walking through the town for their formal begging.
Hakuin not only redefined meditation, he also revitalized koan practice among full-time Zen monks and ultimately brought on a renaissance of Rinzai Zen itself. He formalized the idea of several stages of enlightenment (based on his own experience of increasingly deep satori) as well as a practice that supported this growth. But most of all Hakuin was dismayed by what he considered to be the complete misunderstanding of koan practice in Japan. Monks had memorized so many anecdotes about the ancient Chinese masters that they thought they could signify the resolution of a koan by some insincere theatrics.
[0]f the monks who move about like clouds and water, eight or nine out of ten will boast loudly that they have not the slightest doubt about the essential meaning of any of the seventeen hundred koans that have been handed down. . . . If you test them with one of these koans, some will raise their fists, others will shout "katsu," but most of them will strike the floor with their hands. If you press them just a little bit, you will find that they have in no way seen into their own natures, have no learning whatsoever, and are only illiterate, boorish, sightless men.16
Hakuin breathed new life back into koan theory. For instance, he seems the first Japanese master to take a psychological interest in the koan and its workings. He believed a koan should engender a "great doubt" in the mind of a novice, and through this great doubt lead him to the first enlightenment or kensho.17 Initially he had advocated the "Mu" koan for beginners, but late in life he came up with the famous "What is the sound of one hand clapping?"18 As he described this koan in a letter to a laywoman:
What is the Sound of the Single Hand? When you clap together both hands a sharp sound is heard; when you raise the one hand there is neither sound nor smell. . . .
This is something that can by no means be heard with the ear. If conceptions and discriminations are not mixed within it and it is quite apart from seeing, hearing, perceiving, and knowing, and if, while walking, standing, sitting, and reclining, you proceed straightforwardly without interruption in the study of this koan, then in the place where reason is exhausted and words are ended, you will suddenly . . . break down the cave of ignorance.. . . At this time the basis of mind, consciousness, and emotion is suddenly shattered.19
But this is not the end; rather it is the beginning. After a disciple has penetrated this koan, he receives koans of increasing difficulty. From Hakuin's own experience he knew that satori experiences could be repeated and could become ever deeper and more meaningful. Although he himself never chose to overtly systematize and categorize koans, his heirs did not hesitate to do so, creating the structure that is modern Rinzai Zen.
How did Zen finally emerge, after all the centuries and the convolutions? As Hakuin's descendants taught Zen, a monk entering the monastery was assigned a koan chosen by the master. He was expected to meditate on this koan until his kensho, his first glimmer of satori, which might require two to three years. After this a new phase of study began. The monk was then expected to work his way through a program of koans, requiring as much as a decade more, after which he might meditate on his own, in seclusion, for a time longer.20