4 ideas
A shipwrecked British ship's doctor is taken in by the Hins, who work without wages, take what they need, and have no government, money, or crime. They also lack love, art, or honour, and he finds them unbearably empty. He asks to live among the Behins, whom the Hins keep walled off as incurably mad.
A society that removes emotion, status and symbolism can remove material want and conflict, because most waste and violence come from those drives. The same removal also takes away what makes life feel worth living, so a perfectly rational order can be both flawless and uninhabitable. The book makes both halves of this case and does not choose between them.
The Behins organise their lives around abstract terms that point to nothing observable. Because no fact can settle what the words mean, disputes over them can never end, and people will mutilate or kill each other to defend them. Loyalty to the symbol replaces any concern with outcomes, so the emptier the word, the more violence it can command.
Describe your own civilisation's rituals, honours and ideologies literally, as an observer who shares none of their assumptions would, and they read as clinical symptoms. The Hins treat this behaviour as mental illness to be contained, not as culture to be respected. Reframing normal practice as pathology exposes how much of it exists only because everyone already does it.