What is a koan?

A koan is a story, dialogue, question or statement used in the practice of Zen Buddhism. It contains aspects that are generally inaccessible to normal or logical understanding, but which are be accessible at a spiritual level. Koans originate in the sayings and doings of sages, holy persons and legendary figures who are usually teachers subscribing to Buddhism. Koans are said to reflect their awakened or enlightened state of mind. Zen teachers often recite and comment on koans, and some practitioners concentrate on them during meditation.