6 ideas
Early societies survive by forcing everyone into a rigid, hereditary body of custom that makes behavior predictable and makes cooperation possible. Obedience to this fixed law is the first achievement of civilization, because a group that cannot bind its members cannot act together. The same binding later becomes the main obstacle, since it crushes the variation a society needs to improve.
In early history nations compete, and the ones that win are the ones best at fighting. Discipline, obedience, and loyalty are the qualities that make a group win in war. So conquest keeps and spreads societies that have these traits and wipes out loose, disorderly ones, which amounts to natural selection working between groups rather than between individuals.
Progress requires escaping the fixed custom that first made a nation strong. Government by discussion does this: once a question is openly debated, custom has no special authority on it, and an issue opened to argument can never be fully closed again. Discussion therefore makes originality and tolerance normal instead of dangerous.
Government by discussion slows decisions down and makes leaders defend their plans before they act. This trains a habit of calm deliberation and cuts the damage done by energetic mistakes.
National character is not set mainly by biology or climate. It forms when people unconsciously copy whichever model of behavior happens to gain early prestige. Small chance differences get amplified as everyone imitates the dominant type, and those who don't fit are persecuted, so similar groups can end up with very different characters.
Nations move through three stages. First comes the forging of cohesion through hard custom and, often, despotic rule. Next comes a competitive stage in which war selects the most tightly bound groups. Last, for the rare nations that reach it, comes an age of discussion in which variation and debate replace fixed custom. Most societies get stuck in the first stage because the cohesion that saved them also freezes them in place.