An article by Matt Simon in Wired Magazine’s web site illustrates the beliefs of many of our ancestors. For instance:
17th century English minister and scientist Charles Morton wrote a surprisingly well-reasoned, though obviously totally inaccurate, treatise claiming birds migrate to the moon and back every year. Some species seem to disappear entirely, the only logical conclusion is that they set off into space. “Now, whither should these creatures go, unless it were to the moon?” he asked.
Aristotle reckoned that some birds hibernate while others simply transform into different species when winter comes around.
In the 16th century, the great cartographer and writer Olaus Magnus championed the theory that swallows disappear in the winter not because they travel to tropical climes to pick up coconuts, but because they bury themselves in the clay at the bottom of rivers.