- "Since, in the long run, every planetary society will be endangered by impacts from space, every surviving civilization is obliged to become spacefaring -- not because of exploratory or romantic zeal, but for the most practical reason imaginable: staying alive."
- "...in our obsession with antagonisms of the moment, we often forget how much unites all the members of humanity. Perhaps we need some outside, universal threat to make us recognize this common bond. I occasionally think, how quickly our differences worldwide would vanish if we were facing an alien threat from outside this world."
- President Ronald Reagan, United Nations General Assembly, 21 September 1987
- "And pray that there's intelligent life somewhere up in space...
...'cos there's bugger-all down here on Earth"
- Eric Idle, 'Galaxy Song', Monty Python's Meaning of Life
