Why?' is always the most difficult question to answer. You know where you are when someone asks you 'What's the time?' or 'When was the battle of 1066?' or 'How do these seatbelts work that go tight when you slam the brakes on, Daddy?' The answers are easy and are, respectively, 'Seven-thirty in the evening,' 'Ten-fifteen in the morning,' and 'Don't ask stupid questions.
Douglas Adams, The Salmon of Doubt
humor