Mumon Ekai was born in China, but his collection of 48 kôan The Door Without a Door was very influential in various sects of Japanese Zen Buddhism, such as the Rinzai. In fact, even today – eight centuries after its writing – this book is still used. The kôan are short stories that pose a seemingly absurd or illogical problem and that Zen masters use to test the progress of the student, causing them a mental shock that brings them closer to satori (enlightenment). It is about detaching oneself from the rational, from everything preconceived (external influence) and letting oneself be carried away instead by one's own intuition and experimentation, taking a leap beyond a logical explanation or based on the purely sensory. Facing this book is a curious experience. You close it with the most open mind, with the feeling of having understood everything and not having understood anything. You begin to wonder how absurd everything we take for granted really is, that set of laws, norms, prejudices, phrases, teachings, advice, topics, preconceived ideas. They tell us that things are one way and we accept it that way, we never dare to doubt, to reinterpret or simply trust our instinct. But really, how do I know that the color orange is the same color for me as it is for others? Perhaps what to me is orange to someone else would be the equivalent of my blue.