One of the basic tenets of Zen Buddhism is that there is no way to characterize what Zen is. ... It might seem, then, that all efforts to explain Zen are complete wastes of time. But that is not the attitude of Zen masters and students. For instance, Zen koans are a central part of Zen study, verbal though they are. Koans are supposed to be "triggers" which, though they do not contain enough information in themselves to impart enlightenment, may possibly be sufficient to unlock the mechanisms inside one's mind that lead to enlightenment. But in general, the Zen attitude is that words and truth are incompatible, or at least that no words can capture truth.
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Perhaps the most concise summary of enlightenment would be: transcending dualism. Now what is dualism? Dualism is the conceptual division of the world into categories. ... By prefixing the word "division" by the word "conceptual", I may have made it seem that this is an intellectual or conscious effort, and perhaps thereby given the impression that dualism could be overcome simply by suppressing thought (as if to suppress thinking actually were simple!). But the breaking of the world into categories takes place far below the upper strata of thought; in fact, dualism is just as much a perceptual division of the world into categories as it is a conceptual division. In other words, human perception is by nature a dualistic phenomenon--which makes the quest for enlightenment an uphill struggle, to say the least.
At the core of dualism, according to Zen, are words--just plain words. The use of words is inherently dualistic, since each word represents, quite obviously, a conceptual category. Therefore, a major part of Zen is the fight against reliance on words. To combat the use of words, one of the best devices is the koan, where words are so deeply abused that one's mind is practically left reeling, if one takes the koan seriously. Therefore it is perhaps wrong to say that the enemy of enlightenment is logic; rather, it is dualistic, verbal thinking. In fact, it is even more basic than that: it is perception. As soon as you perceive an object, you draw a line between it and the rest of the world; you divide the world, artificially, into parts, and thereby miss the Way.
Here is a short koan which demonstrates the struggle against words:
Shuzan held out his short staff and said: "If you call this a short staff, you oppose its reality. If you do not call it a short staff, you ignore the fact. Now what do you wish to call this?"
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Why is calling it a short staff opposing its reality? Probably because such a categorization gives the appearance of capturing reality, whereas the surface has not even been scratched by such a statement. It could be compared to saying "5 is a prime number". There is so much more--an infinity of facts--that has been omitted. On the other hand, not to call it a staff is, indeed, to ignore that particular fact, miniscule as it may be. Thus words lead to some truths--some falsehood, perhaps, as well--but certainly not to all truth.
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If words are bad, and thinking is bad, what is good? Of course, to ask this is already horribly dualistic, but we are making no pretense of being faithful to Zen in discussing Zen--so we can try to answer the question seriously. I have a name for what Zen strives for: ism. Ism is an antiphilosophy, a way of being without thinking. The masters of ism are rocks, trees, clams; but it is the fate of higher animal species to have to strive for ism, without ever being able to attain it fully. ... Zen is holism, carried to its logical extreme. If holism claims that things can only be understood as wholes, not as sums of their parts, Zen goes one step further, in maintaining that the world cannot be broken into parts at all. To divide the world into parts is to be deluded, and to miss enlightenment.
A master was asked the question, "What is the Way?" by a curious monk.
"It is right before your eyes," said the master.
"Why do I not see it for myself?"
"Because you are thinking of yourself."
"What about you: do you see it?"
"So long as you see double, saying 'I don't', and 'you do', and so on, your eyes are clouded," said the master.
"When there is neither 'I' nor 'You', can one see it?"
"When there is neither 'I' nor 'You', who is the one that wants to see it?"
Apparently the master wants to get across the idea that an enlightened state is one where the borderlines between the self and the rest of the universe is dissolved. This would truly be the end of dualism, for as he says, there is no system left which has any desire for perception. But what is that state, if not death? How can a living human being dissolve the borderlines between himself and the outside world?
Douglas R. Hofstadter, Godel, Escher, Bach: an Eternal Golden Braid