Surely this is the best kind of word, one that unfurls slowly, layer by layer. Library comes from librairie, Old French for "collection of books". Librairie comes from librarium, Latin for "chest of books". Librarium comes from liber, meaning "book, paper, parchment". And liber's original definition? "The inner bark of trees". The word leads you back with impeccable logic to the roots of the object - from book to paper to tree.

That unravelling of meaning - so neat, so gratifying - somehow suits the library. For it is a pure thing, a simple idea: a building where anyone can go and, for free, borrow books, or sit in a corner and read. In recent weeks, many writers and comedians and other People of Note have remembered the libraries they went to as children - the books' plastic coverings, the thrill of nosing around the shelves, hunting for treasure, the fusty smell of the place. Also, the perils: Zadie Smith told of the day her local library posted notice of an amnesty, so that all those who'd been hoarding overdue books (Mrs Smith had a good few) could return them, unpunished.

A library is a childhood place - your own, or your children's. For some reason, adults don't feel the need to spend time in a public library unless it's for very serious reasons: academic study or writing a book. But when you're a child, a library isn't an earnest place, or a place of industry - it is a literary theme park, a bookish Alton Towers, a free pass into another world of monsters and ghosts. That this world might be shuttered (at the time of writing, 517 libraries are being threatened with closure), that these places of childish fantasy might be dismantled, seems unnecessarily cruel, a failure of the imagination.

Undoubtedly there are more urgent, life-or-death concerns: hospitals, schools, wars. Yet what they forget, the powers that be, is that when everything else is sliding and slipping, the one thing you have left is the possibility of escape through your imagination. And that's what a library offers, apart from being a social space, or a computer room, or a community centre, or an information point, or whatever else the people want it to be; it's a portal for dreamt-up adventure, a rocket to the moon. l

Sophie Elmhirst is a freelance writer and former New Statesman features editor.

This article first appeared in the 25 April 2011 issue of the New Statesman, Easter special