Koan

Koan is a story, dialogue, question, or statement in the history and lore of Chan (Zen) Buddhism, generally containing aspects that are inaccessible to rational understanding, yet may be accessible to intuition. A famous Koan is: "two hands clap and there is a sound; what is the sound of one hand?" (Oral tradition, attributed to Hakuin Ekadu, 1685-1768, considered a reviver of the Koan traditon in Japan).