>>11Have you actually read the manga for xXxHolic? I don't remember if it covers it in the anime.
Holic deals heavily with strange things about the world. Power of belief, people left over in lingering sentiments, obscure magics,
dimensions.
Yuuko is referred to as the
dimensional witch for a reason. xXxHolic in particular is a nexus of sorts for a lot of CLAMP's works. It allows Yuuko to peer into, or reference other dimensions that run parallel to their own - In particular, ones which involve alternate existences of people in that story.