The perfect society is where that civilisation has settled on two competing tribes. And has been running stably for some time in that configuration.
Though the narratives of each tribe are their foundation, each may have more than one narrative governing it. But there will only ever be one fundamental narrative managing the control of the tribe's people. All the others are fine, they simply won't have the power to control that tribe's people at scale and are merely secondary derivatives.
REMEMBER: Obedience is the core of this fundamental narrative. It must allow the people to signal their obedience as instruments of authority, above all else. Actually, that is all it needs to be able to do. Obedience and signalling it to the rest of the tribe is more important than any other factor in a perfect society. Abstract principles like morals, stewardship of the land, observing facts, upholding justice through good law etc etc, come a very remote second to one's membership as obedient instruments of authority.
A total of 2 tribes is the ideal configuration for a perfect society. 1 means no competition, a monopoly, which we all know means poorer quality at higher cost. More than 2 means a lot is being wasted on allowing the third to exist, similar to 1. See NOTE1
A civilisations society may well start off with a poor configuration not equal to 2. But eventually it will all come out in the wash and settle on exactly 2. Because this is the ideal configuration for a perfect society.
Now, I'm not suggesting that this perfect society will be one of perfection in justice, love, equality, morals and so on. I am saying that whatever the people comprising it choose to make of it, it will find perfection to that extent when the number of competing tribes equals 2. And any more or less will mean it is not running in its perfect configuration.
NOTE1: e.g. It's a bit like 2 being the ideal number of crypto miners to assure maximum adoption, security and scale. Any more is a total waste and delivers no further benefits despite what the high priests insist.
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