'The varieties of effects resulting from such morbific causes as are capable of rendering more vivid the feelings of the mind' by S. Hibbert (1825).

The transformation of the old notion of apparition into the new concept of hallucination started in earnest at the beginning of the 19th century. Apparitions were naturalized on the argument that in no case were they a response to an external stimulus; and were secularized by challenging the very existence of external spirits or forces. Both arguments are clearly stated in the work on 'Apparitions' by Samuel Hibbert (a chapter of which has been included below as Classic Text No. 69). Although the debate on the ontology and meaning of the 'phantasms of the living' has continued to this day, it has had no influence on the medical concept of hallucination. It is likely that the latter has suffered as a result.