The Japanese word koan (Chin. gongan) refers to a short anecdote or statement from the life and teachings of a famous master. Koans play an important role in the instruction of students in variousand traditions in Japan and China. The master selects a specific saying and assigns it to a student as a task. At first sight, the stories and questions sound absurd and make little sense. They cannot be decoded by normal, rational reasoning. At the same time, they reveal how limited our modes of thought and perception actually are, and thus lead to deeper insight.