EXTERNAL ORGAN • E-FREE TRANSLATION.COM • Definition of External organ

... the hallucination, or are there various possible sorts of causes? Now defects in the eye, or in the optic nerve, to speak roughly, may cause hallucinations from without. An injured external organ conveys a false and distorted message to the brain and to the intelligence. A nascent malady of the ear may produce buzzings, and these may develop into hallucinatory voices. Here be hallucinations from without. But when a patient begins with a hallucination of the intellect, as that ...

— Cock Lane and Common-Sense • Andrew Lang