Though I have already spoken at some length on the subject of kensho or seeing into one's own true nature, I shall say a little more about it. Since kensho is the foundation of Zen, however much we may think about it, we still do not know it, and, however many times we may speak about it, we can never speak too often.
Hakuin Zenji, in his Sokko roku kaien fusetsu, which I have previously quoted, has this further to say:
My humble advice to you distinguished persons who study the profound mystery of the Buddha-dharma is this: Your close examination of yourself must be as urgent as saving your own head were it ablaze your efforts to penetrate into your own original nature must be as tireless as the pursuit of an indispensable thing; your attitude toward the verbal teachings of the buddhas and patriarchs must be as hostile as that toward a deadly enemy.
In Zen, he who does not bring strong doubt to bear upon the koans is a dissolute, knavish good-far-nothing. Therefore it is said: "Underlying great doubt there is great satori; where there is thorough questioning there will be a thoroughgoing experience of awakening."
Do not say: "Since my worldly duties are many and troublesome, I cannot spare time to solidify my doubt firmly," or, "Since my thoughts are always flying about in confusion, I lack the power to apply myself to genuine concentration on my koan."
Suppose that, among the dense crowds of people in the burly-burly of the market place, a man accidentally loses two or three pieces of gold. You will never find anyone who, because the place is noisy and bustling or because he has dropped his pieces of gold in the dirt, will not turn back to look for them. He pushes any number of people about, stirs up a lot of dust, and, weeping copious tears, rushes around searching for his gold. If he doesn't get it back into his own two hands, he will never regain his peace of mind. Do you consider the priceless jewel worn in the hair, your own inherent marvelous Tao, of less value than two or three pieces of gold?
On hearing Hakuin Zenji's kind words of admonition, any person of resolute purpose will certainly have his mettle aroused. But for one who is without aspiration, of course they will be but the recitation of the Nembutsu in a horse's ear. Treasuring such words of admonition in our hearts, and bearing always in mind the conduct of the patriarchs in their daily activities, we face squarely to the koan we have been given, study it faithfully, and work wholeheartedly. We pass beyond time, are not swayed by all kinds of external circumstances, keep our inner mind calm and composed, and make this mind firm and hard as an iron wall. If this concentrated reflection is built up continuously over one year, two years, three years, insight into one's own true nature will inevitably take place.
The realm which is revealed to us once we see into our own true nature is none other than that known in Sanskrit as the Dharmakaya, and, in Japanese, the hosshin Since the Dharmakaya has been explained backward and forward in the works of the various schools that depend upon the scriptures and their commentaries, I shall not take it up from the scholastic point of view. In Rinzai roku, the Zen Master Rinzai speaks about the Dhannakaya this way: "The pure light in each instant of thought is the Dharmakaya Buddha within your awn house."
With the aid of our first koan we attain our first glimpse into the undifferentiated realm of the Dharmakaya. To deepen our insight into this realm, to become acquainted intimately with this, our original home, and to make it our constant dwelling place, we study many koans known as Dharmakaya koans, or, in Japanese, hosshin koans. Let me give you a few examples:
A monk asked Kassan Osho: "What is the Dharmakaya?" "The Dharmakaya is without form," Kassan replied.
A monk once said to Dairyo Osho: "The physical body decomposes. What is the indestructible Dharmakaya?" Dairyn answered with this verse:
"Blooming mountain flowers
Are like golden brocade;
Brimming mountain waters
Are blue as indigo."
When Ummon was asked, "What is the pure Dharmakaya?" he replied: "The flowering hedge [surrounding the privy)."
To Jun Osho's verse on the Dharmakaya was this:
When the cows of Eshu are well fed with grain,
The horses of Ekisha have full stomachs.
This is like saying that, when an American sneezes, an Englishman catches cold. Fu Daishi composed the following verse on the Dharmakaya:
Empty-handed, yet holding a hoe;
Walking, yet riding a water buffalo.
If, on coming upon expressions such as these, you feel as if you were meeting a close relative face to face at a busy crossroad and recognizing him beyond a question of a doubt, then you can be said to understand the Dharmakaya. But, if you use common sense to conjecture about it, or run hither and thither trying to follow the words of others, you will never know the Dharmakaya. An old master has said: "There are many intelligent men, but few who have attained insight into their own real nature." Truly this one thing - seeing into one's own real nature - is the eternal eye of Zen.
But now that we have once achieved kensho, if we stop here and do not go forward another step, we cannot experience the patriarchs' marvelous realm of differentiation. To save ourselves from this misfortune, it is necessary to pass through many intricate koans having to do with differentiation. The Zen term for the complex interlockings of differentiation is kikan, and the koans that have been devised to aid us in successfully dealing with these interlockings are called kikan koans.
In the Hekigan roku there is a passage that reads:
Jade is tested by fire, gold is tested by a touchstone, a sword is tested by a hair, water is tested by a stick. In our school, one word or one phrase, one action or one state, one entrance or one departure, one "Hello!" or one "How are you!" is used to judge the depth of the student's understanding, to observe whether he is facing forward or facing backward. If he is a fellow with blood in his veins, he will immediately go off, shaking his sleeves behind him, and, though you shout after him, he will not come back.
With the help of the kika n koans we release ourselves from the bonds that hold us fast, get out of the sticky morass in which we are floundering, and return to the unfettered freedom of the open fields. Some people may say: "If I have gained insight into my real nature once, that is enough. Why should I go further and study many kikan koans ?" The old masters lashed out at such persons, calling them "earthworms living in the mud of self-accredited enlightenment." "We awaken to Reality suddenly, and are perceiving phenomena right now." As we master the interlockings of differentiation one by one, and our understanding becomes clearer and clearer, Reality becomes increasingly distinct.
The following are some of the koans used to enable us to manipulate these interlockings freely:
Tosotsu Etsu Osho devised three barriers as tests for his students:
1. You pull out the weeds and study the profound mystery only in order to see into your original nature. Where is your original nature at this moment?
2. One who has realized his own original nature escapes from birth-and-death. When the light of your eyes falls to the ground, how will you escape?
3. One who has escaped from birth-and-death knows whither he goes. When the Four Great Elements that compose your body separate, where will you go?
A monk asked Master Joshu: "What is the meaning of Bodhidharma's coming from the West ?" "The cypress tree in the garden," Joshu replied.
Three times the National Teacher Cha called to his attendant, and three times the attendant answered him. The National Teacher said: "I always used to think that I was beholden to you, but all along it was really you who were beholden to me."
We must make our way through the mass of complex interlockings that comprise the realm of differentiation, and enter the inner sanctuary of the patriarchs. To accomplish this, we must train ourselves by concentrated reflection on our koans over and over again. Daie Osho used to say to people: "I have experienced great satori eighteen times, and lost count of the number of small satoris I have had." If even the old masters had to train themselves thus, surely we haven't a moment to waste.
When the power of kensho - the power of seeing into our own true nature - is weak, we cannot alter the karma clinging to us from the past that hinders our attaimnent. If the wisdom that comprehends differentiation is not completely bright, we cannot benefit sentient beings. But to make this differentiation-wisdom bright is a difficult undertaking indeed.