Katy Guest: Giving away books is a recipe for disaster, Nigella Hobbits have a clever way of dealing with useless objects and unwanted gifts. In hobbit speak, such things are known as mathoms, and kept in special mathom holes. Every time a hobbit has a birthday, he or she gives gifts to everyone who attends the party, and in this way mathoms are handed from hobbit to hobbit and make their way all around the Shire. Often, a mathom will find its way back to its original owner. Which, in a slightly less generous way, is what happened to the writers Sophia Waugh and Nigella Lawson last week. The unwitting mathom-swap came to light when Ms Waugh decided to embarrass her friend on Twitter. OK this is complicated. But worth it." she wrote. So I give a copy of my novel to a friend. Let's call her Nigella... Another friend notices a gap in my backlist on her shelf. Turns to eBay. Buys book.... Book arrives signed from me to, say, Nigella. Didn't realise there were troubled times. Tears of joy/laughter from us. Caught out .... But if there is further trouble we are both happy to send a tenner to let's say @Nigella_Lawson. Old friends and all. For those not familiar with Twitter, this means that she has outed the TV cook Nigella Lawson as the friend who gave away her ever-so-thoughtful signed gift. To those not familiar with humans, "tears of joy/laughter" roughly translates as "I was absolutely gutted." In the olden days, or if she had stopped for a minute to think, Ms Waugh might have written Ms Lawson a nice letter or even just not mentioned it at all. Now, thanks to social media, she is mostly known as the woman whose novels nobody had heard of, until they heard that even the author's good friends don't rate them enough to keep them. It is unlikely that Nigella sold the book on eBay herself, since selling things on eBay is a right old faff, and she has just made £25m from the sale of her house. But unfortunately this is not really the point. Giving away unwanted gifts ought to be a noble act of recycling and free from guilt, but everyone knows that it is not. Giving away unwanted gifts is rejecting the warm feelings of the person who gave them, and giving away unwanted books is even worse. So when that book was actually written by the giver, and signed with a personal, handwritten note, it's like taking someone's love and packing it off to Oxfam. As a literary editor, I am familiar with the problem of too many books and not enough room. My home long ago became an extension of my office: I am currently sheltering 50 entries in the Fiction Uncovered prize that I am judging. But the books that mean the most to me are the ones with little pencil notes from friends who have given them to me as gifts. I wouldn't be friends with the kind of person who would write in a book with ink. And when that friend happens to be the author, that makes the book especially precious. If I stay in this job for much longer, unless they devise a way of hanging books from the ceiling above my desk, I shall have to move back to Yorkshire so that I can buy a bigger house. Maybe Nigella has millions of friends who are authors, and maybe they all have much thicker skins than Sophia Waugh and Paul Theroux, who fell out with VS Naipaul many years ago over a very similar incident. But she of all people ought to know that you don't give away books, no matter how tight your shelf space. If £25m won't buy her enough room for a library, she'd better consider getting a Kindle.