In these respects, and in the awakeness of the scryer, crystal pictures differ from hypnagogic illusions.
The seeing of the pictures, as far as we have spoken of it, appears to be a thing unusual, but in no way abnormal, any more than dreams or hypnagogic illusions are abnormal.
The experience of hypnagogic illusions also seems far more rare than ordinary dreaming in sleep. Unfortunately, while these phenomena have been carefully studied by officially scientific characters, in England orthodox savants have disdained to observe crystalgazing, while in France psychologists have too commonly experimented with subjects professionally hysterical and quite untrustworthy.
Hypnagogic hallucinations, intense and sometimes terrifying experiences that occur as the person is falling asleep.
Occasionally, in hypnagogic illusions, the observer can see the picture develop rapidly out of a blot of light or colour, beheld by the closed eyes.