"Carl Sagan (among others) thought that the answer is to be found, tragically, in the final variable [of the Drake equation]: The high probability that advanced civilizations destroy themselves. In other words, this silent universe is conveying not a flattering lesson about our uniqueness but a tragic story about our destiny. It is telling us that intelligence may be the most cursed faculty in the entire universe — an endowment not just ultimately fatal but, on the scale of cosmic time, nearly instantly so."

Charles Krauthammer, on the search for intelligent life and intelligent politics.