What is called the Zen problem, or koan, is likened to a person who has swallowed a ball of red-hot iron. He cannot gulp it down and he cannot spit it out. Or it is like a mosquito biting an iron bull. It is the nature of a mosquito to bite and it is the nature of an iron bull to be unbiteable. Both go on doing what is their nature, and so, nothing can happen. Soon you realize you are absolutely up against it. There is absolutely no answer to this problem, and no way out. Now, what does that mean? If I cannot do the right thing by doing, and I cannot do the right thing by not doing, what does it mean? It means, of course, that I who essayed to do all this is a hallucination. There is no independent self to be produced. There is no way of showing it because it is not there. When you recover from the illusion and you suddenly wake up, you think, "Whew, what a relief." That is called satori.

Words of Wisdom by Alan Watts.