Although Carl Sagan didn't come up with the concept of pareidolia - the idea that humans have a tendency to detect familiar images like faces in random and coincidental patterns in the environment, he certainly helped popularize it. Pareidolia has been used to dismiss things like the faces on Mars that were thought to have possibly been constructed by intelligent life to strange images that appear to be emerging from clouds. Sagan believed this human condition was the result of our being evolutionarily wired to recognize faces from an early age, a trait that has become hyper attenuated over the years so that now we recognize things like Jesus appearing in all sorts of bizarre places. On the other hand, if you are religiously devoted to Jesus, seeing can be believing.
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