Souls
Souls are the essence of life, present in every living creature - even plants and fungi. Each soul regulates one's emotions, and the more life experience it has, the stronger and more valuable it gets. An isolated, bottled soul resembles a thin gas. No one's quite sure where they come from, but in the Neath, souls are ferried to the Far Coast by the Boatman after death, and in the High Wilderness they go to the Blue Kingdom to be judged by the Sapphir'd King.
Even such a crucial part of one's psyche can still be removed. Devils run the trade in souls, and are responsible for most incidents of soul loss. See, it's possible to live without one's soul, but the consequences might be severe, like loss of emotion or memory. Or they might be nothing at all, perhaps a feeling that something's missing. It is also possible, through the right means, to get one's soul back.
There are also a few ways to damage a soul without losing it - but what sane person would do that?
WORK IN PROGRESS
