Necromancy, or talking to the Dead, From the Greek meaning Dead and Divination.
Dead men tell no lies.
Homer wrote about it! Odysseus travels to the underworld to find out about his up-coming voyage after chanting and drinking the sacrificed blood of animals...
It's mention in the Bible—The Book of Deuteronomy 18:9-12 Warning the Israelites against divination of the dead an abomination against God. In Leviticus 20:27 the death penalty was introduced for anyone practicing witchcraft, or divination. King Saul and the Witch of Endor used witchcraft to speak to the Spirit of Samuel. King Saul was not put to death by the people because he was King, but God himself passed judgement on him and put him to death as Samuel prophesied.
Most religious scholars of the middle ages believed it was impossible to speak to the dead, so they decided; people weren't conjuring up the dead, they were summoning demons that took on the appearance of spirits.
Today, Necromancy bridges the occult, practised through séances, sorcery, channeling and spiritualism to evoke spirits to reveal their secrets.
The Encyclopaedia of Occultism refers to Necromancy as a universal art attainable by using many methods.