This acquiring of a new point of view in our dealings with life and the world is popularly called by Japanese Zen students “satori”[5.1] (_wu_ in Chinese). It is really another name for Enlightenment (_anuttara-samyak-saṁbodhi_), which is the word used by the Buddha and his Indian followers ever since his realisation under the Bodhi-tree by the River Nairañjanā. There are several other phrases in Chinese designating this spiritual experience, each of which has a special connotation, showing tentatively how this phenomenon is interpreted. At all events, there is no Zen without satori, which is indeed the Alpha and Omega of Zen Buddhism. Zen devoid of satori is like a sun without its light and heat. Zen may lose all its literature, all its monasteries, and all its paraphernalia; but as long as there is satori in it, it will survive to eternity. I want to emphasise this most fundamental fact concerning the very life of Zen; for there are some even among the students of Zen themselves who are blind to this central fact and are apt to think when Zen has been explained away logically or psychologically or as one of the Buddhist philosophies which can be summed up by using highly technical and conceptual Buddhist phrases, Zen is exhausted and there remains nothing in it that makes it what it is. But my contention is, the life of Zen begins with the opening of satori (_kai wu_ in Chinese).[5.2] Satori may be defined as an intuitive looking into the nature of things in contradistinction to the analytical or logical understanding of it. Practically, it means the unfolding of a new world hitherto unperceived in the confusion of a dualistically-trained mind. Or we may say that with satori our entire surroundings are viewed from quite an unexpected angle of perception. Whatever this is, the world for those who have gained a satori is no more the old world as it used to be; even with all its flowing streams and burning fires, it is never the same one again. Logically stated, all its opposites and contradictions are united and harmonised into a consistent organic whole. This is a mystery and a miracle, but according to the Zen masters such is being performed every day. Satori can thus be had only through our once personally experiencing it.