“When the sun sinks into the sea and darkness broods over the land, a change takes place in the balance of power between good and evil. The Christian God, His angels and humankind hold sway in the daytime, but when the curfew bell has run down the sun all kinds of creatures from the world of evil swarm forth: the unhallowed dead arise from their graves; demons, gnomes and elves come out from their hiding places. Worst of all, among the humans themselves there are traitors to be found: witches and warlocks who are in league with the Devil and his regiment, and with them rule over the world through the night, until the first rays of the sun come to aid the powers of good, so that men may go about their business in reasonable safety.”
This passage from “The Witch’s Garden” by Harold A. Hansen, translated by Muriel Crofts, displays an adequate enough sentiment on the division of night and day and the powers at work in pre- and early modern Western culture. All of this is really to say that Merlin’s request to only speak of himself at night is a bit… sinister. Just what, or whom, does he not want overhearing when he reveals himself?