Zen, important school of East Asian Buddhism that constitutes the mainstream monastic form of Mahayana Buddhism in China, Korea, and Vietnam and accounts for approximately 20 percent of the Buddhist temples in Japan. The word derives from the Sanskrit dhyana, meaning “meditation.” Central to Zen teaching is the belief that awakening can be achieved by anyone but requires instruction in the proper forms of spiritual cultivation by a master. In modern times, Zen has been identified especially with the secular arts of medieval Japan (such as the tea ceremony, ink painting, and gardening) and with any spontaneous expression of artistic...