Myths of the Norsemen From the Eddas and Sagas
Chorus of Witches.
“On to the Brocken the witches are flocking—
Merry meet—merry part—how they gallop and drive,
Yellow stubble and stalk are rocking,
And young green corn is merry alive,
With the shapes and shadows swimming by.
To the highest heights they fly,
Where Sir Urian sits on high—
Throughout and about,
With clamour and shout,
Drives the maddening rout,
Over stock, over stone;
Shriek, laughter, and moan,
Before them are blown.”
Goethe’s Faust (Anster’s tr.).
As the swallow, cuckoo, and cat were held sacred to Freya in heathen times, these creatures were supposed to have demoniacal attributes, and to this day witches are always depicted with coal-black cats beside them. 
Chapter XI: Uller
The God of Winter
Uller, the winter-god, was the son of Sif, and the stepson of Thor. His father, who is never mentioned in the Northern sagas, must have been one of the dreaded frost giants, for Uller loved the cold and delighted in travelling over the country on his broad snowshoes or glittering skates. This god also delighted in the chase, and pursued his game through the Northern forests, caring but little for ice and snow, against which he was well protected by the thick furs in which he was always clad.
As god of hunting and archery, he is represented with a quiver full of arrows and a huge bow, and as the yew furnishes the best wood for the manufacture of these weapons, it is said to have been his favourite tree. To have a supply of suitable wood ever at hand ready for use, Uller took up his abode at Ydalir, the vale of yews, where it was always very damp.
“Ydalir it is called,
Where Ullr has
Himself a dwelling made.”
Sæmund’s Edda (Thorpe’s tr.).
As winter-god, Uller, or Oller, as he was also called, was considered second only to Odin, whose place he usurped during his absence in the winter months of the year. During this period he exercised full sway over Asgard and Midgard, and even, according to some authorities, took possession of Frigga, Odin’s wife, as related in the myth of Vili and Ve. But as Uller was very parsimonious, and never bestowed any gifts upon mankind, they gladly hailed the return of Odin, who drove his supplanter away, forcing him to take refuge either in the frozen North or on the tops of the Alps. Here, if we are to believe the poets, he had built a summer house into which he retreated until, knowing Odin had departed once more, he again dared appear in the valleys.
Uller was also considered god of death, and was supposed to ride in the Wild Hunt, and at times even to lead it. He is specially noted for his rapidity of motion, and as the snowshoes used in Northern regions are sometimes made of bone, and turned up in front like the prow of a ship, it was commonly reported that Uller had spoken magic runes over a piece of bone, changing it into a vessel, which bore him over land or sea at will.