4 ideas
The Islandians split love into separate named feelings: amia (love of friends), alia (love of place, land and family line), apia (sexual desire), and ania (the wish to marry and share a permanent life). Because they are different feelings with different names, no one expects one person to satisfy all four. Confusing apia with ania, as Americans routinely do, is treated as the source of mismatched marriages.
John Lang arrives as American consul, charged with promoting trade, and falls for Dorna, sister of his Islandian friend Dorn. She rejects him and marries King Tor instead. After an affair with Nattana, Lang returns to America to test his loyalty, then comes back to settle on an Islandian farm with an American wife, Gladys, who struggles to adapt. His official job was to open the country, but he ends up adopting its way of life instead.
Islandian families hold the same farms across many generations and bury their dead on them. This gives each person alia, a felt bond with a specific place and lineage that anchors identity and grounds contentment. The book argues this rootedness produces a slow, unhurried life that a mobile, industrial society cannot give, because it trades place for opportunity.
Islandia's politics centers on whether to repeal its near-total exclusion of foreigners. Lord Mora's party argues for trade, modernization and foreign concessions, and Lord Dorn's party argues that commerce would dissolve the society's customs. The Council votes to stay closed. The novel presents this as a rational choice: a society may accept being materially poorer to keep a way of life its members value more than wealth.