A tweet from Stephen Fry appears to have sent a book about the afterlife from the murky depths of the book sales lists to the dazzling heights of number two. The online retailer Amazon yesterday reported a 6,000% rise in sales for Sum: Forty Tales from the Afterlives by David Eagleman. It went from number 3,629 to number two and the only discernible reason is this tweet from Fry: "You will not read a more dazzling book this year than David Eagleman's Sum. If you read it and aren't enchanted I will eat 40 hats." The tweet was retweeted by Fry followers – hence the dramatic rise.