When, every few years, you see a bite taken out of the sun or moon, you ought to remember just how frightening that question used to be. It became clockwork when the right viewpoint was eventually discovered by science (imagining yourself high above the north pole, looking at the shadows cast by the earth and the moon). But there was an intermediate stage of empirical knowledge, when the shaman discovered that the sixth full moon after a prior eclipse had a two-third's chance of being associated with another eclipse. And so when the shaman told people to pray hard the night before, he was soon seen as being on speaking terms with whomever ran the heavens. This helped convert part-time shamen into full-time priests, supported by the community. This can be seen as the entry-level job for philosophers and scientists, who prize the discoveries they can pass on to the next generation, allowing us to see farther, always opening up new questions while retiring old ones. It's like climbing a mountain that keeps providing an even better viewpoint.
WILLIAM H. CALVIN is a neurobiologist at the University of Washington, who writes about brains, evolution, and climate. His recent books are The Cerebral Code, How Brains Think, and (with the linguist Derek Bickerton) Lingua ex Machina.