Zen Buddhism reveals the inner most dimension of our being and existence. The real being is Buddha–nature (Bodhi-Chitta). It is a Satori. Satori is pathless. The quantum question which was raised by Socrates in 3rd century B.C. in form of Know Thy Self is being repeated again today by Nobel laureate scientists like Einstein, Heisenberg, Erwin Schrodinger and other in all most in the same linguistic and philosophical form ‘what we are’. ‘Where from we have come’. This is the question. Zen’s answer this quantum question is ‘We are all awakened being’ ‘We are all Buddhas’. All the mystical schools and traditions have revealed this truth by their seers and saints. God of mysticism is not a person, it is a principle. God is a myth and metaphor. Zen Buddhism is a mysticism. It is an esoteric technique to rid the man from the snares of false subjectivities and to take him to the enlightenment (Satori). Zen is not a philosophy. It is not a religion. It is a spirituality. It is a pathless path. Zen is a song of silence. Zen is a happy and harmonious blending of science and spirituality. This edition of Zen Buddhism has been revised and I have added a new chapter as Prologue.