For more than seven centuries the Mumonkan has been used in Zen monasteries to train monks and to encourage the religious development of lay Buddhists. It contains forty- eight koans , or spiritual riddles, that must be explored during the course of Zen training. Shibayama Zenkei (1894-1974), an influential Japanese Zen teacher and calligrapher who traveled and lectured throughout the United States in the 60s and 70s, offers his own commentary alongside...