This is the cosmic tree, the “ideogram of Scandinavian mythology” (Mircea Eliade). It corresponds to the Skambha, the cosmic pillar of the Vedas, to the Saxon Irminsûl, and to the World Tree of the Sámi people in Lappland. It is also called Læraðr and Mímameiðr (“Mímir’s Tree”). It is an ash tree, the center and support of the world that it summarizes and symbolizes, the source of life and all knowledge, and all fate. Neither fire nor steel can scathe it, and its fruits heal the womb ailments of women.
Living beneath its three roots are men, frost giants, and the dead in Hel’s realm. According to one tradition, one of its roots leads to the world of the Æsir in the sky. This is where the springs of Urðr (a Norn), Mímir (a giant), and Hvergelmir (the source of all rivers) are located. The dragon Niðhöggr also lives here. The second root goes to Jötunheimr, the world of the giants, and the third to Niflheimr, the world of the dead.
An eagle perches at its top. This is most likely Hræsvelgr (“Carrion Eater”), the flapping of whose wings gives birth to the winds—as well as the falcon Veðrfölnir (“Ash Covered by the Wind”?). The squirrel Ratatoskr climbs up and down the trunk. Five stags graze on its branches: Dáinn and Dvalinn (“Death” and “Torpid”; these are also dwarf names), Duneyrr (“Downy Ears”), and Duraþrór and Eikþyrnir (“Oak-thorny”), as well as the goat Heiðrún. Eight reptiles gnaw on its roots: Niðhöggr, Góinn, Móinn, Grafvitnir, Grafvölluðr, Grábakr, Ófnir, and Sváfnir (we may note in passing that alliterations are generally a sign of the antiquity of the elements). Each day the Norns sprinkle water and light clay over Yggdrasill. The Æsir customarily hold their deliberations beneath the cosmic tree near Urðr’s fountain.
Yggdrasill ensures the vertical coherence of the world, while the Midgard Serpent guarantees its horizontal coherence.