The festival of Samhain was the most sacred of all Celtic festivals. Its rituals helped link people with their ancestors and the past. The Celts believed that the dead rose on the eve of Samhain and that ancestral ghosts and demons were set free to roam the earth.
Since spirits were believed to know the secrets of the afterlife and the future, the priests of the Celts, the Druids, held that on the eve of Samhain predictions had more power and omens could be read with more clarity. They divined the health of the tribe, the wisdom of a proposed move, the right time to make magic or the key to curing a sickness.