KRAEPELIN'S DEFINITION OF HALLUCINATIONS AND ILLUSIONS
In 1913 the German psychiatrist Emil Wilhelm Magnus Georg Kraepelin (1856-1926) defined hallucinations and * illusions as follows: "On behalf of clinical consideration, Esquirol, and after him for practical purposes the majority of researchers, have discriminated between two kinds of sensory misperceptions, namely those in which there is no external stimulus source whatsoever:hallucinations, and those that can only be considered a forgery of a genuine perception by means of one's own additions:illusions."
References
Kraepelin, E. (1913).Psychiatrie. Ein Lehrbuch für Studierende und Ärzte. I. Band. Allgemeine Psychiatrie. Achte, vollständig umgearbeitete Auflage. Leipzig: Verlag von Johann Ambrosius Barth.