This is a complete explanation of Zen practice written by one of the most eminent masters of pre-modern Japan. The author, Torei Enji (1721-1792), was best known as one of two "genius assistants" to Hakuin Ekaku, who was himself a towering figure in Zen Buddhism who revitalized the Rinzai school. Torei was responsible for much of the advanced work of Hakuin's later disciples and also helped systemize Hakuin's teachings. The Undying Lamp of Zen includes a range of principles and practices, from the most elementary to the most advanced. It is an indispensable aid to the practice of Rinzai Zen, and provides an accessible entrée to the Zen experience in general. Torei is a compelling guide, his tone is energetic, no-nonsense, and full of personality. Premier translator Thomas Cleary provides a thorough introduction and illuminating footnotes throughout, and his masterful translation allows Torei's distinctive voice to shine through.