Satori is not a morbid state of mind, a fit subject for the study of abnormal psychology. If anything, it is a perfectly normal state of mind. When I speak of mental upheaval, one may be led to consider Zen as something to be shunned by ordinary people. This is a most mistaken view of Zen, but one unfortunately often held by prejudiced critics. As Joshu declared, "Zen is your everyday thought"; it all depends on the adjustment of the hinge whether the door opens in or opens out. Even in the twinkling of an eye the whole affair is changed and you have Zen, and you are as perfect and as normal as ever. More than that, you have acquired in the meantime something altogether new. All your mental activities will now be working to a different key, which will be more satisfying, more peaceful, and fuller of joy than anything you ever experienced before. The tone of life will be altered. There is something rejuvenating in the possession of Zen. The spring flowers look prettier, and the mountain stream runs cooler and more transparent. The subjective revolution that brings about this state of things cannot be called abnormal. When life becomes more enjoyable and its expense broadens to include the universe itself, there must be something in Satori that is quite precious and well worth one's striving after.