[expand]
The nine worlds’ arrangement on Yggdrasil encoded several important principles about existence’s structure.
Hierarchy Is Vertical:
The stacked realms suggested hierarchy—Asgard above, Helheim below, with Midgard in middle. But this was not simple good-above-evil-below arrangement. Each realm had its necessity, its proper function. Even Helheim served purpose, housing dead, providing realm for those not chosen for Valhalla.
All Levels Are Connected:
Despite distinct realms, all were part of single structure, connected through Yggdrasil, capable of influencing each other. What happened in Asgard affected Midgard. Giants in Jotunheim threatened divine order. The dead in Helheim would emerge at Ragnarok. Isolation was impossible; every realm was part of integrated system.
Boundaries Are Permeable:
Despite distinctions between realms, travel was possible. Gods visited Jotunheim. Giants entered Asgard. Humans occasionally accessed divine or giant-realms. The boundaries were real but not absolute, maintained through vigilance rather than physical impossibility.
The Center Must Hold:
Yggdrasil itself was what prevented cosmic collapse. If the tree fell, all realms would fall. The constant attention to the tree’s health—Norns watering it, gods defending it against excessive damage—demonstrated that cosmic order required active maintenance, that structure was not automatic but achievement, that collapse was always possible if vigilance failed.
[/expand]