Þjazi was also known as Jörmungandr ("animated cattle", "the mighty stick", "animated staff"), and logically this Jörmungandr, better known as the serpent of Miðgarðr, was a son of Loki -- the lightning that brought the mistletoe to the Earth. In the myth about Þórr and the serpent we learn that Jörmungandr was cast down into the abyss when Þórr hit him in the head with a hammer. The original meaning of the word hammer is "stone", and this is what the spirits in the sky were using to bring about the lightning. They sent the Sun's energy to Earth, when the lightning hit the trees. In a myth about Þjazi Loki was stuck to Þjazi, because he hit him with a stick that got stuck, and he could not let go of it. Loki was the fire from the sky, the lightning, that attached itself to the wood.
Loki was the reason Baldr was killed, and the reason Nanna died from grief. The mistletoe had been cut down from the oak tree, by the sorcerer (by Hoðr, the "blind" man who refused to believe in gods, and instead still practised sorcery), because Loki had given him the life force of the oak tree, the mistletoe, so it was Loki's task to get it back. Like Heimdallr Loki had no access to the realm of the dead, so he had to borrow a "bird skin" from Freyja ("spare", "free", "love"). Just like Heimdallr he disguised himself and used the "bird skin" to gain access. He met Iðunn in the realm of the dead, turned her into a nut and brought her back home.
Yet another myth describing the New Year's Eve holiday's religious content is the myth about Þrýmir ("thunder", "bang"). He had stolen Þórr's hammer and taken it to Jötunheimr, far below the surface of the Earth. Þrýmir is yet another name for Þjazi, whose house is called Þrýmheimr. The power of the Sun is in this myth described as the hammer itself, the force that transfers solar power from Heaven to Earth. Heimdallr advised Þórr and Loki to dress up as women, disguising themselves as Freyja and her maid, to gain access to the Jötunheimr and find the hammer. The god of death had free access to the realm of death, but Freyja had too; of course, she was a goddess of the Earth. Hades was located in the Earth, in her womb. The deities always disguised themselves as the god of death or as Freyja, to find the Sun or the Sun's energy and to bring it back.
Óðinn placed his eye in the grave, in the well of the past, every year, in order to learn from the past. This might sound strange, but his eye was the Sun, Baldr, that lost its power every autumn and therefore had to spend the winter in the world of the dead. In other words; Óðinn had one eye in the world of the living and one eye in the world of the dead, at any time, and he could therefore freely travel between these realms, and was regarded as the god who escorted the spirits of the dead to Hel. Because so many gods disguised themselves as him, to gain access to Hel, many of the myths we know about Óðinn are in fact not about Óðinn himself, but about different gods who disguise themselves as Óðinn. He himself did not undertake these many journeys, but his name was used because it was him they impersonated.
A relevant myth in this context is the myth about Óðinn and Suttungr ("new concerns", "young sickness"). Óðinn turned himself into a serpent and crawled into a hole in Hnitbjörg ("nail built mountain"), the home of Suttungr, to steal his mead (made from the blood of the wisest man in the world). It was not a man made mountain, nailed together, but a barrow with a ship inside. He met Suttungr's daughter, Gunnlöð ("invitation to fight"), who was very difficult and tough. He softened her up with sorcery. The mead was stored in three tanks: Óðrœrir ("touch of the mind"), Són ("sounds", "atonement") and Boðn ("bid", "warning"). He spent three nights with her and drank the mead from one tank each night. When he had drunk it all he turned himself into a bird and flew away. Suttungr saw him, turned into an eagle and gave chase. When they arrived in Ásgarðr ("the spirit garden") he suffered the same fate as Þjazi. The other gods lit a fire and set fire to his feathers: he fell down and they beat him to death.
The god (i. e. king) who made this journey had already disguised himself as Óðinn, but to gain access to the realm of the dead he also had to escort a dead person, or else he had no business being there. The god therefore brought the cut down mistletoe, the body of Baldr, and used it as a key to open up the road to Hel. In this myth it is described as a worm; Bölþorn, alias Jörmungandr. The same mistletoe was used as a magic wand to soften up Gunnlöð; she calmed down because when she saw the wand (the mistletoe, a. k. a. the body of Baldr) she realised that he had a valid reason to be there.
Óðinn's meeting with Gunnlöð is described in another myth as well, where she is called by a different name, Rindr ("channel in the ground", "ditch"). In this myth Óðinn travelled to Hel to find a son who could avenge the killing of Baldr. He first had to (in a bride's race) defeat Höðr, Hel's husband, who in this myth is called Ullr ("wool", "cover up", "surround"), before he could lure her into bed. At first he failed to lure her into bed. He tried to threaten her, but she still refused to comply. Finally he had to, just like Heimdallr, Loki and Þórr, dress up, like a woman, to get her into bed. He then took her by force, so that Rindr became pregnant and gave him a son, Váli ("chosen", "fallen").
When we know all of this we easily understand the song about Óðinn in Hávamál; he hanged himself in the sacrificial tree, Heimdallr (alias Yggdrasill), and hung there for nine nights, tasting neither food nor drink, before he fell down into the grave and picked up the runes (secrets). He also learned nine spells (songs) from Bölþorn.
We must realise that these mysteries were created in a time when man did not know that the sexual intercourse was what made the women pregnant. The myths about Óðinn who met Gunnlöð/Rindr are therefore not the original myths; they must have been changed in the transition from matriarchy to patriarchy. They only needed to be slightly changed; originally they told about a meeting with the goddess, where the god (i. e. king) asked for Baldr to be allowed to return, and where he learned the secrets of life from her songs (spells). He himself was reborn as Váli, the chosen one so he still produced that new son he needed to avenge the death of Baldr. When he left the burial mound, the divine womb of the Earth goddess, he was born anew as Váli, when the Sun rose the first day of the new year, in Váli's month (house), Valaskjálfr ("the tremors of the fallen/chosen"). Váli was born in a dramatic play, trembling, shaking and screaming as he entered the world from the realm of the dead. Only one day old he was thus able to hunt down and kill Höðr, and avenge the death of Baldr.
In reality, after the dramatic birth of the newly initiated, the initiated men left for the forest to hunt Höðr/Ullr, the autumn and winter darkness. They did what was only logical; they hunted down and killed the animals that were seen as the spirit animals of winter. In Scandinavia this was the bear and the wolf, but in other parts of Europe they killed other animals instead or as well, and the religious hunt lasted for nine days. This was the nine days Óðinn hung in the sacrificial tree, the nine days it took to reach Hel. The clothes of these initiates still hung in the trees, while they themselves ran naked and unprotected through the forest, armed only with spears, clubs, shields, bows and arrows. Those who managed to kill such an animal stole the life force of the animal, and became berserks.