Early necromancy was likely related to shamanism, which calls upon spirits such as the ghosts of ancestors. Classical necromancers addressed the dead in "a mixture of high-pitch squeaking and low droning", comparable to the trance-state mutterings of shamans.
Necromancy was widespread throughout Western antiquity with records of its practice in Babylon, Egypt, Greece, and Rome. In his Geographica, Strabo refers to νεκρομαντία (necyomanteis), or "diviners by the dead", as the foremost practitioners of divination amongst the people of Persia, and it is believed to have also been widespread amongst the peoples of Chaldea (particularly the Sabians, or star-worshipers), Etruria, and Babylonia. The Babylonian necromancers were called Manzazuu or Sha'etemmu, and the spirits they raised were called Etemmu.
The oldest literary account of necromancy is found in Homer’s Odyssey. Under the direction of Circe, a powerful sorceress, Odysseus travels to the underworld in order to gain insight about his impending voyage home by raising the spirits of the dead through the use of spells which Circe has taught him. He wishes to invoke and question the shade of Tiresias in particular; however, he is unable to summon the seer's spirit without the assistance of others. The Odyssey's passages contain many descriptive references to necromantic rituals: rites must be performed around a pit with fire during nocturnal hours, and Odysseus has to follow a specific recipe, which includes the blood of sacrificial animals, to concoct a libation for the ghosts to drink while he recites prayers to both the ghosts and gods of the underworld.
Rituals such as these were common practices associated with necromancy and varied from the mundane to the grotesque. Rituals in necromancy involved magic circles, wands, talismans, bells, and incantations. Also, the necromancer would surround himself with morbid aspects of death, which often included wearing the deceased's clothing and the consumption of unsalted, unleavened black bread and unfermented grape juice, which symbolized decay and lifelessness. Some necromancers even went so far as taking part in the mutilation and consumption of corpses. These rituals could carry on for hours, days, or even weeks, leading up the eventual summoning of spirits. Often they took place in graveyards or other melancholy venues that suited specific guidelines of the necromancer. Additionally, necromancers preferred summoning the recently departed, citing that their revelations were spoken more clearly; this timeframe usually consisted of twelve months following the death of the body. Once this time period lapsed, necromancers would summon the deceased’s ghostly spirit to appear instead.
Although some cultures may have considered the knowledge of the dead to be unlimited, ancient Greeks and Romans believed that individual shades knew only certain things. The apparent value of their counsel may have been a result of things they had known in life, or of knowledge they acquired after death. Ovid writes in his Metamorphoses of a marketplace in the underworld where the dead can exchange news and gossip.
There are also several references to necromancers – called "bone-conjurers" amongst Jews of the later Hellenistic period – in the Bible. The Book of Deuteronomy (18:9–12) explicitly warns the Israelites against engaging in the Canaanite practice of divination from the dead:
9When thou art come into the land which the LORD thy God giveth thee, thou shalt not learn to do according to the abominations of those nations. 10There shall not be found among you any one who maketh his son or his daughter to pass through the fire, or who useth divination, or an observer of times, or an enchanter, or a witch, 11or a charmer, or a consulter with familiar spirits, or a wizard, or a necromancer. 12For all who do these things are an abomination unto the LORD, and because of these abominations the LORD thy God doth drive them out from before thee (KJV).
This warning was not always heeded. One of the foremost examples is when King Saul had the Witch of Endor invoke the shade of Samuel, a judge and prophet, from Sheol using a ritual conjuring pit (1 Samuel 28:3–25). Some Christian writers later rejected the idea that humans could bring back the spirits of the dead and interpreted such shades as disguised demons instead, thus conflating necromancy with demon summoning.
Caesarius of Arles entreats his audience to put no stock in any demons or gods other than the Christian God, even if the working of spells appears to provide benefit. He states that demons only act with divine permission and are permitted by God to test Christian people. Caesarius does not condemn man here; he only states that the art of necromancy exists, although it is prohibited by the Bible