"Ford was very kind - he gave the barman another five-pound note and told him to keep the change. The barman looked at it and then looked at Ford. He suddenly shivered: he experienced a momentary sensation that he didn't understand because no one on Earth had ever experienced before. In moments of great stress, every life form that exists gives out a tiny subliminal signal. This signal simply communicates an exact and almost pathetic sense of how far that being is from its place of birth. On Earth it is never possible to be farther than sixteen thousand miles from your birthplace, which really isn't very far, so such signals are too minute to be noticed. Ford Prefect was at this moment under great stress and he was born six hundred light-years away in the near vicinity of Betelgeuse."
- The Hitchhiker's Guide to the Galaxy