One may question whether or not satori is a real experience or merely a philosophical ideal which evolved in the history of Zen thought. Two independent sources of evidence indicate that there is such an experience. One source is the recent electroencephalographic (EEG or brain wave) studies of Zen meditators. 2 The other source is the case histories and testimonies of persons allegedly realizing satori in recent years. Both these two areas of study require further investigation before any definite conclusions can be made, and probably the characteristic Zen EEG tracings are not akin to the subjective experiences described in the case histories. In other words they appear to be two unrelated phenomena. Also, it may be that both of these recently-studied phenomena are quite different from the satori experiences of the Zen masters of old or of those Zen monks residing today in secluded and highly disciplined meditation centres.