Well, okay, the letter wasn’t really scarlet; it was black, but nevertheless … Beginning in 1882, when the Bodleian Library overhauled its cataloguing system, the Greek letter phi (Φ) was branded onto the spines of books deemed to be “Obscene literature in general” or “Drawings and photographs of nudes and similar subjects.” These books — which ran from an illustrated edition of Ovid’s love poetry to Joyce’s Ulysses to Madonna’s Sex to a Monty Python volume — were kept under lock and key, available only with a specific referral from a professor. The Φ system was in use until, wait for it, 2010.