The oldest Stave church in Norway at Urnes
Brian Bates sees the Yggdrasil Tree as representing Sleipnir, the spirit horse of Odin, a great eight legged creature that takes him down to the otherworld. Bates works his way from the word Yggdrasil, Ygg being a nickname for Odin and drasil a word for horse. Odin of course famously hung from the tree for 9 days but it was during this time, a time of spiritual quest and dreaming that the tree transformed into Sleipnir. And Bates points out that the gallows in Anglo-Saxon times were also known as "a 'horse' upon which its victim rode to death".
Sleipnir carries Odin on his ride round the nine sacred cosmos of knowledge, Sleipnirs eight legs representing eight of the worlds, with Odin representing the ninth. Of course, Tolkien also had a great horse in the Lord of The Rings, this was Shadowfax, and there is a dramatic moment in the film, when the great army of Gandalf stands high on a steep hill, Shadowfax, gleaming white to the fore, and then they sweep down this impossibly steep hill to destroy the myriad trolls and terrible creatures on the plain below that are harassing the fort. Tolkien describes Shadowfax "as being foaled in the morning of the world". The tale of Odin's descent into the Lowerworld is for another day, it was a place that contained wisdom, but of course it also contained the dead spirits, which at that liminal time of the year allhalloween, would seep gently into our world, curling and spinning round the houses ;)
Detail from the Greensted Church
Detail from the Greensted church