Are book users cheating?

Everybody agrees that if you use an engine to play chess then you are a cheat. However I would like to know why the many players on this site who admit to using a book or database for the first 20 moves or whatever are not also considered cheats. I often read sentences like 'I was still in book until move 18...'
Surely doing whatever a book or database tells you is the same as doing whatever an engine tells you? I've never seen a professional in the world championships sitting with a chess book in front of him during a match.
Maybe there is a simple explanation for this but I can't think of it.

(b) While a game is in progress you may not refer to chess engines, chess computers or be assisted by a third party. Endgame tablebases may not be consulted during play but you may reference books, databases consisting of previously played games between human players, and other pre-existing research materials.

Originally posted by Stephen King
I would like to know why the many players on this site who admit to using a book or database....
Surely doing whatever a book or database tells you is the same as doing whatever an engine tells you? I've never seen a professional in the world championships sitting with a chess book in front of him during a match.

Thanks.
Okay so officially it's allowed but isn't it the same as 3rd party help. Still means that a player with the ability of a 1200 can follow a book and maybe beat someone a lot higher without actually knowing why they made the moves they did.

Originally posted by Stregone
I suspect that there's a difference between referring to a book and some chess engine. But you make a good point: "I've never seen a professional...."

it's CC chess.....i'm here to learn....i don't use engines but i do use an opening book....why?....cause thats what CC chess is for!!

Back in the 80's when dudes were playing CC chess.....they didn't sit there and stare at the board for weeks on end.....they researched the moves from previous games...the extra time gives us feedom to learn the opening played.....

The point?...i use a book here....so when i am at at tournament i know what the hell i am doing. now if you don't mind....i need to get some whiskey....you guys stress me man.

Okay thanks for the explanation.
I see what you mean about the best players using this site as a place to practise their openings and theory. You're right that I have no idea how deep theory goes.
I still think it's possible that people around my level can just use a book and win unfairly.

I've never tried so wouldn't know how hard it is to use a database to win as a lower level player so I'll take you're word for it that it's not possible.

Well, one argument to consider is whether memory is really skill? Are you cheating if you have an uncanny ability to memorize the openings? After all, it's not based on your skill or your ability to understand the moves you're making. You're just referring to the book in your head.

So maybe the databases are equalizers against people with better memory.

Okay it's clear to me now. Thanks for taking the time to explain it.

Originally posted by Stephen King
Everybody agrees that if you use an engine to play chess then you are a cheat. However I would like to know why the many players on this site who admit to using a book or database for the first 20 moves or whatever are not also considered cheats. I often read sentences like 'I was still in book until move 18...'
Surely doing whatever a book or data f him during a match.
Maybe there is a simple explanation for this but I can't think of it.