FOREL'S DEFINITION OF ILLUSIONS

   In 1903 the Swiss psychiatrist, hypnotist, and entomologist August Forel (1848-1931) defined illusions as follows. "By illusion... we mean an incomplete hallucination, in which, for example, one sees some friend with a black face, fiery eyes, and horns on his head, when the friend is really there, but the diabolical accessories are not."

   References

   Forel, A. (1907). The hygiene of nerves and mind in health and disease. Translated by Aikins, H.A. New York, NY: G.P. Putnam's Sons.