Lost to the mysts of time and catastrophe, the fabled Zhao Zwehian Library has reappeared. Or at least, part of it has...
"The wind-driven snow parts for the barest of seconds, revealing a glimpse of refuge from the deadly storm. It’s a massive sapphire pyramid. Yet you know of nothing like it in this area…"
When you sleep, your soul briefly returns to the place where it was created/goes to when it dies, and seeks nourishment. Everybody's soul is created with a little link (or you could say a greater entity calls it back) to that place so that it can return easily, but upon death, the soul returns via that and annihilates the link as if returns.
Also, as an added thingy, you could say the entity supplying the link, or residue of the links themselves, (whichever) is the source of all arcane power.