In the old days they made you look diabolic.
He used prayer and fasting to deliver himself from evil enchantment; and when he saw ecstatic and mystical visions promising him the Lord's help and great usefulness in the Lord's work, he feared that these revelations might be of diabolic origin.
So Merlin preserves his diabolic origin; Arthur his mystic coming and his mystic passing; while Gawain, and after him Lancelot, journey across the river, as the Irish hero Bran had done before them to the island of fair women - the Celtic vision of the realm of death.
In the formulae of blessings that follow, the special efficacy against devils is implied by the aspersion with holy water; the benedictions themselves are usually merely invocative of the divine protection or assistance, though, e.g., in the form for blessing sick animals the priest prays that "all diabolic power in them may be destroyed, and that they may be ill no longer."
Some Evangelical clergymen discovered by this means that the spirits who caused the movements were of a diabolic nature, and some amazing accounts were published in 1853 and 1854 of the revelations obtained from the talking tables.