The Yule Log
The burning of the Yule Log is a pagan winter solstice (and later Christmas) tradition practiced among numerous cultures in northern Europe and Scandinavia.
During the Yule celebration, Nordic and Germanic pagans would drag a huge tree or log into the hall and burn it for several days of feasting and revelry. At the end of the Yule celebration, a piece of the log was saved to lite the log of next year’s Yule.
Christmas Unwrapped - The History of Christmas, History Channel (1995)
ps — I’m looking for more sources on this topic, if anyone has a good recommendation, please send it my way!