In 1880 the Belgian cage, a device that was intended to restrain the severely mad, was demonstrated at a national exhibition in Brussels. It consisted of a cage standing on short posts with a small opening for meals to be passed through. Engraving by William Pryor Letchworth, 1889. Insanity, craziness or madness is a spectrum of behaviors characterized by certain abnormal mental or behavioral patterns. Insanity may manifest as violations of societal norms, including a person becoming a danger to themselves or others, though not all such acts are considered insanity. In modern usage, insanity is most commonly encountered as an informal unscientific term denoting mental instability, or in the narrow legal context of the insanity defense. In the medical profession the term is now avoided in favor of diagnoses of specific mental disorders; the presence of delusions or hallucinations is broadly referred to as psychosis. When discussing mental illness in general terms, "psychopathology" is considered a preferred descriptor.