Tomorrow, December 21, is the Winter Solstice. The Winter Solstice is the shortest day of the year, or, if you are a glass half-full kind of person, the longest night of the year. It marks a turning point - towards longer days and moving towards spring. These long-nights, especially those between Christmas and Epiphany were a time of much superstition in olden times.
During the Twelve Nights, old superstitions persisted that even more frightening otherworldly beings also wandered the earth. It was thought best to be safe inside with the door barred during the Twelve Nights and hope that Odin and his cortege of spectral hunters, wolves, and lost souls would quickly pass overhead.
In other areas (such as enclaves of the Balkans and Slavic lands), fearsome creatures from the underworld - malevolent werewolfe-like goblins who dwelt underground the rest of the year - roamed above ground during these nights. They attempted to enter houses through the chimney. To keep safe, embers were kept burning on the hearth all night long. The goblins were driven away for another year by the ceremonial "blessing of the waters" on Epiphany.
Fishermen also believed that the sea was not safe during the Twelve Days, so they stayed in port from Christmas Day until the waters of the sea were also blessed in the ceremonies on Epiphany.
The Ride of the Valkyries, Arthur Rackham