Mark Forsyth - author of the Sunday Times Number One bestseller The Etymologicon - reveals in this essay, specially commissioned for Independent Booksellers Week, the most valuable thing about a really good bookshop.Along the way he considers the wisdom of Donald Rumsfeld, naughty French photographs, why Elizabeth Bennet and Mr Darcy would never have met online, and why only a bookshop can give you that precious thing - what you never knew you were looking for.

Mark Forsyth is a blogger and author whose books have made him one of the UK's best-known commentators on words. His book The Etymologicon was a Sunday Times Number One bestseller and was followed by the similarly successful The Horologicon and The Elements of Eloquence. Follow Mark on Twitter @inkyfool