Stolen from their former lives, Changelings have to balance what they have become with what they returned to. They cannot deny their time in Arcadia and the changes that altered them there, but at the same time, it is their strong connection to this world that allowed them to return, and they feel a need to identify with and be accepted by the world around them.
Clarity tracks this delicate balance between the mundane world and the maddening realms of Glamour. A changeling with high Clarity is able to easily distinguish between the two worlds and might even become slightly more adept at spotting supernatural phenomena otherwise hidden from view. By contrast, a changeling with low Clarity finds her perceptions spiraling out of control. She starts having trouble distinguishing her dreams from reality, and starts mixing up elements from the two worlds.
If a changelings let a non-changeling know that they are a changeling, they instantly have to roll to see how far they drop in clarity.
- Changeling: The Lost Rulebook, p. 26, 28, 75, 91-93, 211, 235