These cases will be sufficient to show what mental process one has to go through with before the opening of satori takes place. Of course these are prominent examples and highly accentuated, and every satori is not preceded by such an extraordinary degree of concentration. But an experience more or less like these must be the necessary antecedent to all satori, especially to that which is to be gone through with at the outset of the study. The mirror of mind or the field of consciousness then seems to be so thoroughly swept clean as not to leave a particle of dust on it. When thus all mentation is temporarily suspended, even the consciousness of an effort to keep an idea focussed at the centre of attention is gone, that is, when, as the Zen followers say, the mind is so completely possessed or identified with its object of thought that even the consciousness of identity is lost as when one mirror reflects another, the subject feels as if living in a crystal palace, all transparent, refreshing, buoyant, and royal. But the end has not yet been reached, this being merely the preliminary condition leading to the consummation called satori. If the mind remains in this state of fixation, there will be no occasion for its being awakened to the truth of Zen. The state of “Great Doubt” (_tai-gi_), as it is technically known, is the antecedent. It must be broken up and exploded into the next stage, which is looking into one’s nature or the opening of satori. The explosion, as it is nothing else, generally takes place when this finely balanced equilibrium tilts for one reason or another. A stone is thrown into a sheet of water in perfect stillness, and the disturbance at once spreads all over the surface. It is somewhat like this. A sound knocks at the gate of consciousness so tightly closed, and it at once reverberates through the entire being of the individual. He is awakened in the most vivid sense of the word. He comes out baptised in the fire of creation. He has seen the work of God in his very workshop. The occasion may not necessarily be the hearing of a temple bell, it may be reading a stanza, or seeing something moving, or the sense of touch irritated, when a most highly accentuated state of concentration bursts out into a satori.