Was that they never really explained how Extraction was invented or what uses it had other than crime. If there are any. But I guess that it would have some potentially very interesting uses in psychology, if we accept that theories of the subconscious mind are true and whatnot. But I digress. My point was that it seems like there is a whole history and subculture to Dreamwalking (I can't think of anything else to call it ) that we don't get told about. It must be a rather common thing, if Fischer had been trained to guard against it. Maybe Ariadne was in a school that teaches Dreaming in addition to architecture. Or maybe Caine has a secret life as a criminal Architect in addition to being a psych professor. But I feel like there has to also be legitimate uses for those kind of skills ...