Replica of a Roman military diploma discharging an auxiliary and granting him citizenship, bronze, based on 1st century AD original
I think about the Roman Empire quite a bit
Same. It's a fascinating polity.
Empires doing empire things, like running pyramid schemes of infinite growth. Until there's no more spoils to share.
what
I claim that empire (the Roman empire as well as other empires before and after it) has always been a pyramid scheme, and granting citizenship was a way to keep the scheme running in Rome (Roman soldiers would fight to conquer more lands for the empire, and in return be granted citizenship and some of the conquered lands.) This could only work in an ever-expanding empire, and in that is it is somewhat similar to the 'infinite growth' narratives of modern times.