Arriving back at the dorm late one evening, my roommate explained that she had gotten lost in the school library. No one was surprised, since the library is large and has a confusing layout.

When I asked how long it took her to find an exit, she admitted she hadn't actually found the exit herself. She had used an emergency phone to call for help. Puzzled, I asked, "How did your rescuers find you if you didn't know where you were?"

"Easy," she said. "I started reading titles of books around me, and they located my position from the card catalogue."