Also called aether. The theory is that all beings produce aether (which can also be found in the air, which is how aether can also drive dirigibles), or soul. Those who produce the normal amount of aether are regular mortals; humans. Those who produce an excess amount can become a ghost, vampire or werewolf. Those who do not produce any are preternaturals. The amount of internally produced aether is essentially the amount of soul one possesses. Creative types are thought to have a higher chance of having excess soul, and therefore being able to survive a vampire or werewolf metamorphosis, or become ghosts after death. Unfortunately, a normal human has no way of knowing whether he or she has excess soul until death, making metamorphosis a risky prospect.

A prominent Italian theory is that soul is connected to the processing of ambient aether through the skin, hence why a preternatural pulls the excess soul from a person through touch.

There are multiple atmospheres of aether, through which dirigibles and other flying contraptions can navigate.