A cacodemon (or cacodaemon) is an evil spirit or (in the modern sense of the word) a demon. The opposite of a cacodemon is an agathodaemon or eudaemon, a good spirit or angel. The word cacodemon comes through Latin from the Ancient Greek κακοδαίμων kakodaimōn, meaning an "evil spirit," whereas daimon would be a neutral spirit in Greek and Tychodaimon would be a good spirit. In psychology, cacodemonia (or cacodemomania) is a form of insanity in which the patient believes that they are possessed by an evil spirit. The first known occurrence of the word cacodemon dates to 1398. In Shakespeare's Richard III Act 1 Scene 3, Queen Margaret calls Richard a "cacodemon" for his foul deeds and manipulations.