I am a book annotator. Of course I never write in the margins of library books, and I wouldn’t dream of marking books lent by a well-meaning friend: I’m a book annotator, not a sociopath. But a pencilled note or punctuation mark in the margin of my own books is a form of ownership, a tiny graphite beacon for future browsing and (on occasion) an aid to concentration. Most of these notes are unobtrusive – a line here, an asterisk there – but there is one book that I own which is annotated to the point of deranged excess: the Penguin Classic by Gregory of Tours, entitled The History of the Franks and translated by Lewis Thorpe.