Yggdrasil

Creatures live within Yggdrasil, including the dragon Níðhöggr, the squirrel Ratatoskr, the hawk Veðrfölnir, and the stags Dáinn, Dvalinn, Duneyrr and Duraþrór.

In the second stanza of the Poetic Edda poem Völuspá, the völva (a shamanic seeress) reciting the poem to the god Odin says that she remembers far back to "early times", being raised by jötnar, recalls nine worlds and nine ídiðiur (rendered in a variety of ways by translators—Dronke, for example, provides "nine wood-ogresses"), and when Yggdrasil was a seed ("glorious tree of good measure, under the ground").

The maidens "incised the slip of wood", "laid down laws" and "chose lives" for the children of humanity and the destinies (ørlǫg) of men.

The völva describes, as a part of the onset of Ragnarök, that Heimdallr blows Gjallarhorn, that Odin speaks with Mímir's head, and then: Yggdrasill shivers, the ash, as it stands.

Stanza 32 details that a squirrel named Ratatoskr must run across Yggdrasil and bring "the eagle's word" from above to Níðhöggr below.

Stanza 33 describes that four harts named Dáinn, Dvalinn, Duneyrr and Duraþrór consume "the highest boughs" of Yggdrasil.

Beneath the root that reaches the frost jötnar is the well Mímisbrunnr, "which has wisdom and intelligence contained in it, and the master of the well is called Mimir".

High continues that the norns that live by the holy well Urðarbrunnr each day take water from the well and mud from around it and pour it over Yggdrasil so that the branches of the ash do not rot away or decay.

High provides more information about Urðarbrunnr, cites a stanza from Völuspá in support, and adds that dew falls from Yggdrasil to the earth, explaining that "this is what people call honeydew, and from it bees feed".

[20] In chapter 54, as part of the events of Ragnarök, High describes that Odin will ride to the well Mímisbrunnr and consult Mímir on behalf of himself and his people.

After this, "the ash Yggdrasil will shake and nothing will be unafraid in heaven or on earth", and then the Æsir and Einherjar will don their war gear and advance to the field of Vígríðr.

This seems to be a very ancient conception, perhaps based on the Pole Star, the centre of the heavens, and the image of the central tree in Scandinavia may have been influenced by it....

"[26] Rudolf Simek theorizes that the survival of Líf and Lífþrasir through Ragnarök by hiding in Hoddmímis holt is "a case of reduplication of the anthropogeny, understandable from the cyclic nature of the Eddic eschatology".

Simek says that Hoddmímis holt "should not be understood literally as a wood or even a forest in which the two keep themselves hidden, but rather as an alternative name for the world-tree Yggdrasill.

Simek additionally points out legendary parallels in a Bavarian legend of a shepherd who lives inside a tree, whose descendants repopulate the land after life there has been wiped out by plague (citing a retelling by F. R. Schröder).

In addition, Simek points to an Old Norse parallel in the figure of Örvar-Oddr, "who is rejuvenated after living as a tree-man (Ǫrvar-Odds saga 24–27)".

[27] Continuing as late as the 19th century, warden trees were venerated in areas of Germany and Scandinavia, considered to be guardians and bringers of luck, and offerings were sometimes made to them.

A massive birch tree standing atop a burial mound and located beside a farm in western Norway is recorded as having had ale poured over its roots during festivals.

Davidson notes that the gods are described as meeting beneath Yggdrasil to hold their things, and the related Irminsul, which may have been a pillar, was also symbolic of the center of the world.

Davidson details that it would be difficult to ascertain whether a tree or pillar came first, and that this is likely to depend on whether the holy location was in a thickly wooded area or not.

[28] Ken Dowden comments that behind Irminsul, Thor's Oak in Geismar, and the sacred tree at Uppsala "looms a mythic prototype, an Yggdrasil, the world-ash of the Norsemen".

[29] Thomas Carlyle adopted "Igdrasil" as a favorite symbol; it features in both On Heroes, Hero-Worship, & the Heroic in History (1841) and Past and Present (1843).

[31] Modern works of art depicting Yggdrasil include Die Nornen (painting, 1888) by K. Ehrenberg; Yggdrasil (fresco, 1933) by Axel Revold, located in the University of Oslo library auditorium in Oslo, Norway; Hjortene beiter i løvet på Yggdrasil asken (wood relief carving, 1938) on the Oslo City Hall by Dagfin Werenskiold; and the bronze relief on the doors of the Swedish Museum of National Antiquities (around 1950) by B. Marklund in Stockholm, Sweden.

[32] In Overlord, a Japanese light novel series written by Kugane Maruyama, Yggdrasil is the name of a popular DMMORPG, where the protagonist got trapped after its shutdown.