The classic definition of Zen, a Japanese form of Buddhism, is: "Zen is Zen". This cautious way shows how direct form of knowledge Zen is. It is a knowledge without anything formally cognitive, which presupposes the overcoming of any cognitive or other effort and constitutes the state of enlightenment, with meditation, of what "knows" and is the embodiment of its knowledge. In this book, texts and excerpts from the literature of Zen are presented, from its distant Indian and Chinese origins to the pure, beautiful haiku.