Asking someone to repeat a phrase you'd not only heard very clearly but were also exceedingly angry about was around Defcon II in the lexicon of squabble.

It's still magic even if you know how it's done.

Once upon a time the plural of 'wizard' was 'war'.

People were stupid, sometimes. They thought the Library was a dangerous place because of all the magical books, which was true enough, but what made it really one of the most dangerous places there could ever be was the simple fact that it was a library.

...Roland de Chumsfanleigh (it wasn't his fault).

It's not worth doing something unless you were doing something that someone, somewere, would much rather you weren't doing.

The truth is that even big collections of ordinary books distort space, as can readily be proved by anyone who has been around a really old-fashioned secondhand bookshop, one that looks as though they were designed by M. Escher on a bad day and has more stairways than storeys and those rows of shelves which end in little doors that are surely too small for a full-sized human to enter. The relevant equation is: Knowledge = power = energy = matter = mass; a good bookshop is just a genteel Black Hole that knows how to read.