I do not intend to enumerate all the varieties of the psychological theory. The most systematic, that of Myers, accepted by Delboef and others, is full of a biological mysticism all its own. Here it is in substance: In every one of us there is a conscious self adapted to the needs of life, and potential selves constituting the subliminal consciousness. The latter, much broader in scope than personal consciousness, has dependent on it the entire vegetative life--circulation, trophic actions, etc. Ordinarily the conscious self is on the highest level, the subliminal consciousness on the second; but in certain extraordinary states (hypnosis, hysteria, divided consciousness, etc.) it is just the reverse. Here is the bold part of the hypothesis: Its authors suppose that the supremacy of the subliminal consciousness is a reversion, a return to the ancestral. In the higher animals and in primitive man, according to them, all trophic actions entered consciousness and were regulated by it. In the course of evolution this became organized; the higher consciousness has delegated to the subliminal consciousness the care of silently governing the vegetative life. But in case of mental disintegration there occurs a return to the primitive state. In this manner they explain burns through suggestion, stigmata, trophic changes of a miraculous appearance, etc. It is needless to dwell on this conception of the unconscious. It has been vehemently criticised, notably by Bramwell, who remarks that if certain faculties could little by little fall into the domain of subliminal consciousness because they were no longer necessary for the struggle for life, there are nevertheless faculties so essential to the well-being of the individual that we ask ourselves how they have been able to escape from the control of the will. If, for example, some lower type had the power of arresting pain, how could it lose it? At the foundation of the psychological theory in all its forms is the unexpressed hypothesis that consciousness may be likened to a quantity that forever decreases without reaching zero. This is a postulate that nothing justifies. The experiments of psychophysicists, without solving the question, would support rather the opposite view. We know that the "threshold of consciousness" or minimum perceptible quantity, appears and disappears suddenly; the excitation is not felt under a determinate limit. Likewise in regard to the "summit of perception" or maximum perceptible, any increase of excitation is no longer felt if above a determinate limit. Moreover, in order that an increase or diminution be felt between these two extreme limits, it is necessary that both have a constant relation--differential threshold--as is expressed in Weber's law. All these facts, and others that I omit, are not favorable to the thesis of growing or diminishing continuity of consciousness. It has even been maintained that consciousness "has an aversion for continuity."