Zen riddles are neither easy nor hard, because they are intended as philosophical questions that promote an individual's spirituality. For instance, one riddle asks what sound is made by a single hand clapping. The riddle is a thought-provoking exercise for a student of Zen and has no definitive answer.
Zen riddles are known as koans. They are used in Zen practice to prompt questioning of the meaning of life and to further a student's progress in the practice of Zen.
Zen is a faction of Buddhism developed in the 6th Century in China. It emphasizes seeking knowledge about the nature of Buddha and using the knowledge in daily challenges. The knowledge is used for helping others. Zen emphasizes interaction with a knowledgeable mentor rather than learning doctrine. Followers of Zen work to improve their clarity and understanding in order to experience a moment of awakening.
The religion has had numerous periods of thought in its history, which spans thousands of years. In the literary period, from 950 to 1250, Zen practitioners began compiling collections of quotations and works by Zen masters, with poetry and comments added. Zen reached broad popularity in the United States in the 1950s and 1960s, in part due to interest from beat poets like Jack Kerouac and Allen Ginsburg.