The first day, when King Arthur looked around, he said to Merlin, who was nearby, “Merlin, it seems to me that it would be a wonderful thing if these candles could burn forever, so that they would never go out, by night or day, either in wind nor in rain.”

‘Truly,” said Merlin, “I’ll make them last longer than you dare hope.” Then he performed his enchantments and said to the king, “King, know that these candles will not go out until my soul leaves my body. On the day they go out, two strange things will occur in this land, for I will be given over to death by the tricks of a woman, and the Knight with Two Swords will strike the dolorous blow" against Our Lord’s prohibition, because of which the adventures of the Holy Grail will occur, especially in the kingdom of Logres. Then will begin troubles and storms all through Great Britain, and they will occur so frequently that everyone who sees them happen will be completely astonished, and without question they will last twenty-two years.”

Post-Vulgate Merlin