If, for three or five years, there is still no satori, then the koan should be dropped; otherwise it may become an invisible chain round one.
You will have started thinking that this is a kind of mantra, a religious ritual – every day you do it. Nothing happens, but perhaps sometime you will accumulate enough virtue…. But what virtue can you accumulate by thinking about a koan like the sound of one hand clapping?
These are not mantras that you go on repeating all your life; these are absolutely scientific devices. But one has to do it with totality, then it can open the door. If you do it half-heartedly, then please don’t do it, because doing it half-heartedly you will never come to the gate. You will go on repeating your nonsense – because it is nonsense; you have to remember that it is nonsense that you are repeating. There is no sound of one hand clapping, and there is no face that you can find anywhere before your parents were born.
These are not puzzles that you can, with great intelligence, solve. They look like puzzles, but they are not puzzles; they are simply absurdities. But the absurd is capable of tiring the mind. Only the absurd can tire it – anything rational, the mind will manage; anything reasonable, the mind will manage; anything logical, the mind will manage. Only something absurd…Mind cannot manage the absurd; it can go nuts but it cannot solve the problem. Before it goes nuts you have to drop the problem.
Remember that either your koan can drive you nuts, if you are doing it half-heartedly, or it can make you a buddha if you are doing it totally, wholeheartedly. The whole question is of urgency and totality.
Before the koan becomes a chain, a bondage, it has to be dropped.
Even these traditional methods can become a medicine which poisons.
In general, meditation has to be done with urgency, but if, after three or five years, the urgency is still maintained forcibly, the tension becomes a wrong one and it is a serious condition.
It can drive you mad. Just think: for five years, day and night, a person is thinking about the sound of one hand clapping. He will go mad! It will become such a psychological condition that he may want to stop it but it will not stop. It will go on and on inside in him, “What is the sound of one hand clapping?” Even in his sleep it will continue. The moment he opens his eyes, the first thought will be, “What is the sound of one hand clapping?” Before going to sleep, the last thought will be, “What is the sound of one hand clapping?” And the same will continue through the whole night like an undercurrent.