The lack of any radio signals or other astronomical evidence supportive of the existence of intelligent extraterrestrial life possessed of technology of sufficient sophistication to bring itself to our attention here on Earth is not, per se, evidence of an absence of life, or even intelligent life, in the cosmos itself, but it does indicate that any such advanced societies, if they have come into existence at all, may be extremely rare and comparatively short-lived, destroyed by the very technology that might have brought them to our notice. This, it will be suggested, is the solution to Fermi’s famous ‘paradox’, and the reason no SETI signals have been detected. The lessons we should learn are that life like that on our planet is very rare and precious, and we must not risk destroying it.