SCIOUSNESS AND NO DISTINCT DEPARTURE FROM BODILY AND MENTAL SANITY a. It would seem that a considerable number of perfectly healthy persons occasionally experience, while in a fully waking state, hallucinations for which no cause can be assigned. The census of hallucinations conducted by the Society of Psychical Research showed that about of all sane persons can remem ber having experienced at least one hallucination while they be lieved themselves to be fully awake and in normal health. These sporadic hallucinations of waking healthy persons are far more frequently visual than auditory, and they usually take the form of some familiar person in ordinary attire. The figure in many cases is seen, on turning the gaze in some new direction, fully developed and lifelike, and its hallucinatory character may be re vealed only by its noiseless movements, or by its fading away in situ. A special interest attaches to hallucinations of this type, owing to the occasional coincidence of the death of the person with his hallucinatory appearance. The question raised by these coincidences will be discussed in a separate paragraph below.
b. A few persons, otherwise normal in mind and body, seem to experience repeatedly some particular kind of hallucination. The voice (oaiµovLov) so frequently heard by Socrates, warning or advising him, is the most celebrated example of this type.