Hakuin Ekaku (1685–1769) is one of the most influential figures in Zen Buddhism. He revitalized the Rinzai Zen tradition (which emphasizes the use of koans, or unanswerable questions, in meditation practice), and all masters of that school today trace their lineage back through him. He is responsible for the most famous of all koans: "What is the sound of one hand clapping?" He is also famous for his striking and humorous art, which he also regarded as teaching. This book provides a rare, intimate look at Hakuin the man, through his personal correspondence. Beating the Cloth Drum contains twenty-eight of Hakuin's letters to students, political figures, fellow teachers, laypeople, and friends. Each letter is accompanied by extensive commentary and notes. They showcase Hakuin's formidable, thoughtful, and sometimes playful personality—and they show that the great master used every activity, including letter-writing, as an opportunity to impart the teachings that were so close to his heart.