In 1633, at age eleven, Bankei Yotaku was banished from his family's home because of his consuming engagement with the Confucian texts that all schoolboys were required to copy and recite. Using a hut in the nearby hills, he wrote the word Shugyo-an, or "practice hermitage," on a plank of wood, propped it up beside the entrance, and settled down to devote himself to his own clarification of "bright virtue."

He finally turned to Zen and, after fourteen years of incredible hardship, achieved a decisive enlightenment, whereupon the Rinzai priest traveled unceasingly to the temples and...