Hakuin Ekaku was one of the most influential figures in Japanese Zen Buddhism. He transformed the Rinzai school from a declining tradition that lacked rigorous practice into a tradition that focused on arduous meditation and koan practice. Essentially all modern practitioners of Rinzai Zen use practices directly derived from the teachings of Hakuin.

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• You know the sound of two hands clapping; tell me, what is the sound of one hand?

• Until he hears the sound of one hand, everything he does is bad.