• I was on a walking tour of Oxford colleges once with a group of bored and unimpressable tourists. They yawned at Balliol's quad, T.E. Lawrence's and Churchill's portraits, and the blackboard Einstein wrote his E=mc2 on. Then the tour guide said, 'And this is the Bridge of Sighs, where Lord Peter proposed (in Latin) to Harriet,' and everyone suddenly came to life and began snapping pictures. Such is the power of books.