Wumen Huikai (Japanese: Mumon Ekai) was a Chinese Chán master during China’s Song period. Born in the Hangzhou prefecture of China, he is most famous for having compiled and commentated the 48-kōan collection The Gateless Barrier. In its famous first kōan, known as the “mu kōan,” Chan master Zhaozhou Congshen is asked whether a dog has the Buddha nature. As a young monk, Wumen is said to have spent six years struggling with the kōan.
