Iain M. Banks said this quote

Everything was a metaphor; all things were something other than themselves. The pain, for example, was an ocean, and he was adrift on it. His body was a city and his mind a citadel. All communications between the two seemed to have been cut, but within the keep that was his mind he still had power. The part of his consciousness that was telling him the pain did not hurt, and that all things were like other things, was like...like...he found it hard to think of a comparison. A magic mirror, maybe.