Yggdrasil (Old Norse Yggdrasill or Askr Yggdrasils) is the mighty and gigantic tree, whose trunk rises at the geographical centre of the Norse spiritual cosmos. The essentials elements of that cosmos, including the Nine Worlds, are arrayed around it and bound together by its branches and roots, which connect the various parts of the cosmos to one another. The welfare of the cosmos depends on the well-being of Yggdrasil. When the tree trembles, it indicates the awakening of Ragnarok, the destruction of the universe.
The first element in Yggdrasil’s name, Yggr (“Terrible”), is one of the countless names of the god Odin and indicates how powerful and terrifying the Vikings imagined him to be.
The second element, drasill, means “horse.” So, Yggdrasil’s name means “Horse of Odin,” a reference to the time when the Terrible one sacrificed himself to discover the runes : the tree was his gallows and bore his limp body, which the Norse poetic imagination described metaphorically as a horse and a rider.
In Old Norse literature, Yggdrasil is commonly said to be an ash tree, but at other times, it’s said that no one knows the species to which the magnificent tree belongs.
In the words of the Old Norse poem Völuspá, Yggdrasil is “the friend of the clear sky,” so tall that its crown is above the clouds. Its heights are snow-capped like the tallest mountains, and “the dews that fall in the dales” slide off from its leaves. Poem Hávamál adds that the tree is “windy,” surrounded by frequent, fierce winds at its heights. “No one knows where its roots run,” because they stretch all the way down to the underworld, which no one (except shamans) can see before he or she dies. The gods hold their daily council at the tree.
Numerous animals are believed to live on Yggdrasil’s stout branches and roots. Around its base lurk the dragon Nidhogg and several snakes, who gnaw at its roots. An unnamed eagle perches in its upper branches, and a squirrel, Ratatoskr (Drill-Tooth), scurries up and down the trunk conveying the dragon’s insults to the eagle and vice versa. Meanwhile, four stags – Dainn, Dvalinn, Duneyrr, and Durathror – graze on the tree’s leaves.
Animals and their activities may be amusing but they also hold a deeper and significant meaning. The image of the tree being nibbled away bit by bit by several beasts depicts its mortality, and along with it, the mortality of the cosmos that depends on it.
The Old Norse sources provide vivid but contradictory accounts of the number and arrangement of the roots and wells beneath the base of Yggdrasil’s trunk. According to the poem Grímnismál, Yggdrasil has three main roots: one planted in Midgard, the world of mankind; one in Jotunheim, the world of the giants; and one in Hel, the underworld.
Nevertheless, there are some clues in the sources that might enable us to construct a tentative and partial schema of where some of the Nine Worlds would have been generally thought to be located. They seem to have been arranged along two axes, one vertical, the other horizontal.
The vertical axis would correspond to Yggdrasil’s trunk, with Asgard in the highest branches, Midgard on the ground at the tree’s base, and Hel underground amongst the tree’s roots. The horizontal axis would be based on the distinction the Vikings made between the innangard and utangard. Thus, Asgard would be right over the trunk of the tree, Midgard around the trunk (and therefore in the “middle” on both axes), and Jotunheim would surround Midgard and thereby be that much more distant from the trunk.
In any case, we can see how vital to the Norse worldview Yggdrasil was felt to be by the number of earthly trees the Vikings treated as representations of the great world-tree.
Yggdrasil represents the cycle of birth, growth, death, and rebirths. As such, it is a symbol often used in Viking Jewellery, both throughout history and today, either on its own, or together with runes.