When a particular bunch of social-climbing monkeys arrived on the scene,
however, they began to ask suck questions. The better the monkeys got at
answering those questions, the more baffling the universe became; knowledge
increases ignorance. The message they got was: Up There is very different from
Down Here.
They didn't know that Down Here was a pretty good place for creatures like
them to live. There was air to breathe, animals and plants to eat, water to
drink, land to stand on, and caves to get out of the rain and the lions. They
did know that it was changeable, chaotic, unpredictable ...
They didn't know that Up There - the res of the universe - isn't like that.
Most of it is empty space, a vacuum. You can't breate vacuum. Most of what
isn't vacuum, is huge balls of overheated plasma. You can't stand on ball of
flame. And most of what isn't vacuum and isn't burning is lifeless rock. You
can't eat rock. They were going to learn this later on. What they DID know was
that Up There was, in human timescales, calm, ordered, regular. And
predictable too - you could set your stone circle by it.
All this gave rise to general feeling that Up There was different from Down
Here for a REASON. Down Here was cleary designed for US. Equally clearly, Up
There wasn't. Therefore it must be designed for _somebody else_. And the new
humanity was already speculating about some suitable tenants, and had been
ecer since they'd hidden in the caves from the thunder. The gods! They were Up
There, looking Down! And they were clearly in charge, because humanity
certainly wasn't. As a bonus, that explained all of the things Down Here, that
were a lot more complicated that anything visible Up There, like thunderstoms
and earthquakes and bees. Those were under the control of the gods.

Science of the Discworld by T. Pratchett, I. Stewart & J. Cohen.