DEMONOLOGY. – Demonology studies beliefs concerning spirits or demons. Primitive peoples imagine that every living thing, insofar as it is endowed with an animating spirit, is animated by such a spirit; and they attribute to spirits or souls—such as the wandering souls of the dead—all effects whose causes are not readily apparent. Furthermore, the attribution to spirits of extraordinary and mysterious power, which always inspires a reverential fear, has led to their being regarded as demons within the sphere of religion, where they have come to serve, alongside the gods, as intermediaries between these and humanity.
Many demons are of human origin, being the souls of the deceased who remain on earth outside the *Adel*. Such are the souls of heroes, protectors of a people or a city, who were believed to dwell near their tombs, often in the form of a serpent, the animal that inhabits the underworld.
Generally, the souls of the unburied or those who died violently wander the earth, troubling the living, especially those responsible for their misfortune. Among the Greeks, the Furies were the souls of the slain, desirous of vengeance, which later became infernal furies vindicating parricide and perjury.
Spirits are invisible, having bodies composed of subtle matter, such as air or vapor, and they live freely, though sometimes being bound to a natural object. When they manifest themselves, they assume often indeterminate and confused forms—giants, dwarfs, corpulent or emaciated figures, and so on.
As for their abode, demons fill the elements with their presence, but they especially prefer places far from human habitation, deep in valleys or on mountains, in the depths of forests or the expanses of deserts. Demons can sometimes be beneficial to humans; in such cases, the Furies themselves were called Eumenides. But generally, demons seek to harm humanity, darkening the sun and moon, producing storms, tempests, floods, earthquakes, droughts, famines, diseases, and the death of men and animals; it may be said that every misfortune has its own special demon. At times, one or more spirits obsess the body of an individual, depriving them of all freedom of action. The existence of demons has been invoked to explain many physical phenomena, as well as to resolve the problem of the origin of evil, which, in the stage of polydaemonism, was attributed to evil spirits. In polytheism, good was reserved for the gods, while evil was assigned to demons, who were perpetually at war with the former.
In Greece, demons entered philosophy, particularly in Stoic and Neoplatonic thought, as rational beings serving as intermediaries between the gods and humanity. Some monotheistic religions have also accommodated demonology, to the extent that it is compatible with the idea of a single God.