Sherlock Holmes and Dr Watson went camping.
They pitch their tent under the stars and go to sleep.
Sometime in the middle of the night Holmes wakes Watson up.
"Watson, look up at the stars, and tell me what you deduce."
Watson says, "I see millions of stars and even if a few of those have planets, it's quite likely there are some planets like Earth, and if there are a few planets like Earth out there, there might also be life."
Holmes replied: "Watson, you idiot, somebody stole our tent!"