Answer:
more advanced technology?
Explanation:
They need to read more of the authors writings to find the key to the story's truths.
I believe they are common because people believe that is where we could be headed. Will we run society into the ground, or will we prosper? Will the society be a "Divergent" or "Giver" society or will it exist as it does today? Since we have no way of knowing, we pretend we do.
That the Roman Empire was a gargantuan power and reached to almost all of the known world at the time of greatest land holdings