Mumonkan - The Gateless Barrier: Version1, Version2 (PDF's)
The Wu-men-kuan, better known in its Japanese pronunciation Mumonkan, was compiled in 1228 by the monk Wu-men Hui-k’ai (Japanese: Mumon Ekai). It consists ofa series of forty-eight koans, meditation questions given to Zen students when they have reached a point in their practice where they can quiet and focus their minds. The first koan given to Zen students has usually been the first case here, Chao-chous dog and the meaning of Mu (Chinese: Wu, “not have”).